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 <linux/trace_clock.h>
  50#include <asm/byteorder.h>
  51
  52MODULE_LICENSE("GPL");
  53MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
  54
  55static int fqs_duration;
  56module_param(fqs_duration, int, 0444);
  57MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us), 0 to disable");
  58static int fqs_holdoff;
  59module_param(fqs_holdoff, int, 0444);
  60MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  61static int fqs_stutter = 3;
  62module_param(fqs_stutter, int, 0444);
  63MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  64static bool gp_exp;
  65module_param(gp_exp, bool, 0444);
  66MODULE_PARM_DESC(gp_exp, "Use expedited GP wait primitives");
  67static bool gp_normal;
  68module_param(gp_normal, bool, 0444);
  69MODULE_PARM_DESC(gp_normal, "Use normal (non-expedited) GP wait primitives");
  70static int irqreader = 1;
  71module_param(irqreader, int, 0444);
  72MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  73static int n_barrier_cbs;
  74module_param(n_barrier_cbs, int, 0444);
  75MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
  76static int nfakewriters = 4;
  77module_param(nfakewriters, int, 0444);
  78MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  79static int nreaders = -1;
  80module_param(nreaders, int, 0444);
  81MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  82static int object_debug;
  83module_param(object_debug, int, 0444);
  84MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
  85static int onoff_holdoff;
  86module_param(onoff_holdoff, int, 0444);
  87MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
  88static int onoff_interval;
  89module_param(onoff_interval, int, 0444);
  90MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  91static int shuffle_interval = 3;
  92module_param(shuffle_interval, int, 0444);
  93MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  94static int shutdown_secs;
  95module_param(shutdown_secs, int, 0444);
  96MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), <= zero to disable.");
  97static int stall_cpu;
  98module_param(stall_cpu, int, 0444);
  99MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 100static int stall_cpu_holdoff = 10;
 101module_param(stall_cpu_holdoff, int, 0444);
 102MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 103static int stat_interval = 60;
 104module_param(stat_interval, int, 0644);
 105MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
 106static int stutter = 5;
 107module_param(stutter, int, 0444);
 108MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
 109static int test_boost = 1;
 110module_param(test_boost, int, 0444);
 111MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 112static int test_boost_duration = 4;
 113module_param(test_boost_duration, int, 0444);
 114MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 115static int test_boost_interval = 7;
 116module_param(test_boost_interval, int, 0444);
 117MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 118static bool test_no_idle_hz = true;
 119module_param(test_no_idle_hz, bool, 0444);
 120MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
 121static char *torture_type = "rcu";
 122module_param(torture_type, charp, 0444);
 123MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 124static bool verbose;
 125module_param(verbose, bool, 0444);
 126MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
 127
 128#define TORTURE_FLAG "-torture:"
 129#define PRINTK_STRING(s) \
 130        do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 131#define VERBOSE_PRINTK_STRING(s) \
 132        do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 133#define VERBOSE_PRINTK_ERRSTRING(s) \
 134        do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 135
 136static char printk_buf[4096];
 137
 138static int nrealreaders;
 139static struct task_struct *writer_task;
 140static struct task_struct **fakewriter_tasks;
 141static struct task_struct **reader_tasks;
 142static struct task_struct *stats_task;
 143static struct task_struct *shuffler_task;
 144static struct task_struct *stutter_task;
 145static struct task_struct *fqs_task;
 146static struct task_struct *boost_tasks[NR_CPUS];
 147static struct task_struct *shutdown_task;
 148#ifdef CONFIG_HOTPLUG_CPU
 149static struct task_struct *onoff_task;
 150#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 151static struct task_struct *stall_task;
 152static struct task_struct **barrier_cbs_tasks;
 153static struct task_struct *barrier_task;
 154
 155#define RCU_TORTURE_PIPE_LEN 10
 156
 157struct rcu_torture {
 158        struct rcu_head rtort_rcu;
 159        int rtort_pipe_count;
 160        struct list_head rtort_free;
 161        int rtort_mbtest;
 162};
 163
 164static LIST_HEAD(rcu_torture_freelist);
 165static struct rcu_torture __rcu *rcu_torture_current;
 166static unsigned long rcu_torture_current_version;
 167static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 168static DEFINE_SPINLOCK(rcu_torture_lock);
 169static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 170        { 0 };
 171static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 172        { 0 };
 173static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 174static atomic_t n_rcu_torture_alloc;
 175static atomic_t n_rcu_torture_alloc_fail;
 176static atomic_t n_rcu_torture_free;
 177static atomic_t n_rcu_torture_mberror;
 178static atomic_t n_rcu_torture_error;
 179static long n_rcu_torture_barrier_error;
 180static long n_rcu_torture_boost_ktrerror;
 181static long n_rcu_torture_boost_rterror;
 182static long n_rcu_torture_boost_failure;
 183static long n_rcu_torture_boosts;
 184static long n_rcu_torture_timers;
 185static long n_offline_attempts;
 186static long n_offline_successes;
 187static unsigned long sum_offline;
 188static int min_offline = -1;
 189static int max_offline;
 190static long n_online_attempts;
 191static long n_online_successes;
 192static unsigned long sum_online;
 193static int min_online = -1;
 194static int max_online;
 195static long n_barrier_attempts;
 196static long n_barrier_successes;
 197static struct list_head rcu_torture_removed;
 198static cpumask_var_t shuffle_tmp_mask;
 199
 200static int stutter_pause_test;
 201
 202#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 203#define RCUTORTURE_RUNNABLE_INIT 1
 204#else
 205#define RCUTORTURE_RUNNABLE_INIT 0
 206#endif
 207int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 208module_param(rcutorture_runnable, int, 0444);
 209MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 210
 211#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 212#define rcu_can_boost() 1
 213#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 214#define rcu_can_boost() 0
 215#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 216
 217#ifdef CONFIG_RCU_TRACE
 218static u64 notrace rcu_trace_clock_local(void)
 219{
 220        u64 ts = trace_clock_local();
 221        unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 222        return ts;
 223}
 224#else /* #ifdef CONFIG_RCU_TRACE */
 225static u64 notrace rcu_trace_clock_local(void)
 226{
 227        return 0ULL;
 228}
 229#endif /* #else #ifdef CONFIG_RCU_TRACE */
 230
 231static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 232static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 233DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 234                                        /*  and boost task create/destroy. */
 235static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 236static bool barrier_phase;              /* Test phase. */
 237static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 238static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 239static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 240
 241/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 242
 243#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 244#define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 245#define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 246static int fullstop = FULLSTOP_RMMOD;
 247/*
 248 * Protect fullstop transitions and spawning of kthreads.
 249 */
 250static DEFINE_MUTEX(fullstop_mutex);
 251
 252/* Forward reference. */
 253static void rcu_torture_cleanup(void);
 254
 255/*
 256 * Detect and respond to a system shutdown.
 257 */
 258static int
 259rcutorture_shutdown_notify(struct notifier_block *unused1,
 260                           unsigned long unused2, void *unused3)
 261{
 262        mutex_lock(&fullstop_mutex);
 263        if (fullstop == FULLSTOP_DONTSTOP)
 264                fullstop = FULLSTOP_SHUTDOWN;
 265        else
 266                pr_warn(/* but going down anyway, so... */
 267                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 268        mutex_unlock(&fullstop_mutex);
 269        return NOTIFY_DONE;
 270}
 271
 272/*
 273 * Absorb kthreads into a kernel function that won't return, so that
 274 * they won't ever access module text or data again.
 275 */
 276static void rcutorture_shutdown_absorb(const char *title)
 277{
 278        if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 279                pr_notice(
 280                       "rcutorture thread %s parking due to system shutdown\n",
 281                       title);
 282                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 283        }
 284}
 285
 286/*
 287 * Allocate an element from the rcu_tortures pool.
 288 */
 289static struct rcu_torture *
 290rcu_torture_alloc(void)
 291{
 292        struct list_head *p;
 293
 294        spin_lock_bh(&rcu_torture_lock);
 295        if (list_empty(&rcu_torture_freelist)) {
 296                atomic_inc(&n_rcu_torture_alloc_fail);
 297                spin_unlock_bh(&rcu_torture_lock);
 298                return NULL;
 299        }
 300        atomic_inc(&n_rcu_torture_alloc);
 301        p = rcu_torture_freelist.next;
 302        list_del_init(p);
 303        spin_unlock_bh(&rcu_torture_lock);
 304        return container_of(p, struct rcu_torture, rtort_free);
 305}
 306
 307/*
 308 * Free an element to the rcu_tortures pool.
 309 */
 310static void
 311rcu_torture_free(struct rcu_torture *p)
 312{
 313        atomic_inc(&n_rcu_torture_free);
 314        spin_lock_bh(&rcu_torture_lock);
 315        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 316        spin_unlock_bh(&rcu_torture_lock);
 317}
 318
 319struct rcu_random_state {
 320        unsigned long rrs_state;
 321        long rrs_count;
 322};
 323
 324#define RCU_RANDOM_MULT 39916801  /* prime */
 325#define RCU_RANDOM_ADD  479001701 /* prime */
 326#define RCU_RANDOM_REFRESH 10000
 327
 328#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 329
 330/*
 331 * Crude but fast random-number generator.  Uses a linear congruential
 332 * generator, with occasional help from cpu_clock().
 333 */
 334static unsigned long
 335rcu_random(struct rcu_random_state *rrsp)
 336{
 337        if (--rrsp->rrs_count < 0) {
 338                rrsp->rrs_state += (unsigned long)local_clock();
 339                rrsp->rrs_count = RCU_RANDOM_REFRESH;
 340        }
 341        rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 342        return swahw32(rrsp->rrs_state);
 343}
 344
 345static void
 346rcu_stutter_wait(const char *title)
 347{
 348        while (stutter_pause_test || !rcutorture_runnable) {
 349                if (rcutorture_runnable)
 350                        schedule_timeout_interruptible(1);
 351                else
 352                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 353                rcutorture_shutdown_absorb(title);
 354        }
 355}
 356
 357/*
 358 * Operations vector for selecting different types of tests.
 359 */
 360
 361struct rcu_torture_ops {
 362        void (*init)(void);
 363        int (*readlock)(void);
 364        void (*read_delay)(struct rcu_random_state *rrsp);
 365        void (*readunlock)(int idx);
 366        int (*completed)(void);
 367        void (*deferred_free)(struct rcu_torture *p);
 368        void (*sync)(void);
 369        void (*exp_sync)(void);
 370        void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 371        void (*cb_barrier)(void);
 372        void (*fqs)(void);
 373        int (*stats)(char *page);
 374        int irq_capable;
 375        int can_boost;
 376        const char *name;
 377};
 378
 379static struct rcu_torture_ops *cur_ops;
 380
 381/*
 382 * Definitions for rcu torture testing.
 383 */
 384
 385static int rcu_torture_read_lock(void) __acquires(RCU)
 386{
 387        rcu_read_lock();
 388        return 0;
 389}
 390
 391static void rcu_read_delay(struct rcu_random_state *rrsp)
 392{
 393        const unsigned long shortdelay_us = 200;
 394        const unsigned long longdelay_ms = 50;
 395
 396        /* We want a short delay sometimes to make a reader delay the grace
 397         * period, and we want a long delay occasionally to trigger
 398         * force_quiescent_state. */
 399
 400        if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 401                mdelay(longdelay_ms);
 402        if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 403                udelay(shortdelay_us);
 404#ifdef CONFIG_PREEMPT
 405        if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 406                preempt_schedule();  /* No QS if preempt_disable() in effect */
 407#endif
 408}
 409
 410static void rcu_torture_read_unlock(int idx) __releases(RCU)
 411{
 412        rcu_read_unlock();
 413}
 414
 415static int rcu_torture_completed(void)
 416{
 417        return rcu_batches_completed();
 418}
 419
 420static void
 421rcu_torture_cb(struct rcu_head *p)
 422{
 423        int i;
 424        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 425
 426        if (fullstop != FULLSTOP_DONTSTOP) {
 427                /* Test is ending, just drop callbacks on the floor. */
 428                /* The next initialization will pick up the pieces. */
 429                return;
 430        }
 431        i = rp->rtort_pipe_count;
 432        if (i > RCU_TORTURE_PIPE_LEN)
 433                i = RCU_TORTURE_PIPE_LEN;
 434        atomic_inc(&rcu_torture_wcount[i]);
 435        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 436                rp->rtort_mbtest = 0;
 437                rcu_torture_free(rp);
 438        } else {
 439                cur_ops->deferred_free(rp);
 440        }
 441}
 442
 443static int rcu_no_completed(void)
 444{
 445        return 0;
 446}
 447
 448static void rcu_torture_deferred_free(struct rcu_torture *p)
 449{
 450        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 451}
 452
 453static void rcu_sync_torture_init(void)
 454{
 455        INIT_LIST_HEAD(&rcu_torture_removed);
 456}
 457
 458static struct rcu_torture_ops rcu_ops = {
 459        .init           = rcu_sync_torture_init,
 460        .readlock       = rcu_torture_read_lock,
 461        .read_delay     = rcu_read_delay,
 462        .readunlock     = rcu_torture_read_unlock,
 463        .completed      = rcu_torture_completed,
 464        .deferred_free  = rcu_torture_deferred_free,
 465        .sync           = synchronize_rcu,
 466        .exp_sync       = synchronize_rcu_expedited,
 467        .call           = call_rcu,
 468        .cb_barrier     = rcu_barrier,
 469        .fqs            = rcu_force_quiescent_state,
 470        .stats          = NULL,
 471        .irq_capable    = 1,
 472        .can_boost      = rcu_can_boost(),
 473        .name           = "rcu"
 474};
 475
 476/*
 477 * Definitions for rcu_bh torture testing.
 478 */
 479
 480static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 481{
 482        rcu_read_lock_bh();
 483        return 0;
 484}
 485
 486static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 487{
 488        rcu_read_unlock_bh();
 489}
 490
 491static int rcu_bh_torture_completed(void)
 492{
 493        return rcu_batches_completed_bh();
 494}
 495
 496static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 497{
 498        call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 499}
 500
 501static struct rcu_torture_ops rcu_bh_ops = {
 502        .init           = rcu_sync_torture_init,
 503        .readlock       = rcu_bh_torture_read_lock,
 504        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 505        .readunlock     = rcu_bh_torture_read_unlock,
 506        .completed      = rcu_bh_torture_completed,
 507        .deferred_free  = rcu_bh_torture_deferred_free,
 508        .sync           = synchronize_rcu_bh,
 509        .exp_sync       = synchronize_rcu_bh_expedited,
 510        .call           = call_rcu_bh,
 511        .cb_barrier     = rcu_barrier_bh,
 512        .fqs            = rcu_bh_force_quiescent_state,
 513        .stats          = NULL,
 514        .irq_capable    = 1,
 515        .name           = "rcu_bh"
 516};
 517
 518/*
 519 * Definitions for srcu torture testing.
 520 */
 521
 522DEFINE_STATIC_SRCU(srcu_ctl);
 523
 524static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 525{
 526        return srcu_read_lock(&srcu_ctl);
 527}
 528
 529static void srcu_read_delay(struct rcu_random_state *rrsp)
 530{
 531        long delay;
 532        const long uspertick = 1000000 / HZ;
 533        const long longdelay = 10;
 534
 535        /* We want there to be long-running readers, but not all the time. */
 536
 537        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 538        if (!delay)
 539                schedule_timeout_interruptible(longdelay);
 540        else
 541                rcu_read_delay(rrsp);
 542}
 543
 544static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 545{
 546        srcu_read_unlock(&srcu_ctl, idx);
 547}
 548
 549static int srcu_torture_completed(void)
 550{
 551        return srcu_batches_completed(&srcu_ctl);
 552}
 553
 554static void srcu_torture_deferred_free(struct rcu_torture *rp)
 555{
 556        call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 557}
 558
 559static void srcu_torture_synchronize(void)
 560{
 561        synchronize_srcu(&srcu_ctl);
 562}
 563
 564static void srcu_torture_call(struct rcu_head *head,
 565                              void (*func)(struct rcu_head *head))
 566{
 567        call_srcu(&srcu_ctl, head, func);
 568}
 569
 570static void srcu_torture_barrier(void)
 571{
 572        srcu_barrier(&srcu_ctl);
 573}
 574
 575static int srcu_torture_stats(char *page)
 576{
 577        int cnt = 0;
 578        int cpu;
 579        int idx = srcu_ctl.completed & 0x1;
 580
 581        cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 582                       torture_type, TORTURE_FLAG, idx);
 583        for_each_possible_cpu(cpu) {
 584                cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 585                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 586                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 587        }
 588        cnt += sprintf(&page[cnt], "\n");
 589        return cnt;
 590}
 591
 592static void srcu_torture_synchronize_expedited(void)
 593{
 594        synchronize_srcu_expedited(&srcu_ctl);
 595}
 596
 597static struct rcu_torture_ops srcu_ops = {
 598        .init           = rcu_sync_torture_init,
 599        .readlock       = srcu_torture_read_lock,
 600        .read_delay     = srcu_read_delay,
 601        .readunlock     = srcu_torture_read_unlock,
 602        .completed      = srcu_torture_completed,
 603        .deferred_free  = srcu_torture_deferred_free,
 604        .sync           = srcu_torture_synchronize,
 605        .exp_sync       = srcu_torture_synchronize_expedited,
 606        .call           = srcu_torture_call,
 607        .cb_barrier     = srcu_torture_barrier,
 608        .stats          = srcu_torture_stats,
 609        .name           = "srcu"
 610};
 611
 612/*
 613 * Definitions for sched torture testing.
 614 */
 615
 616static int sched_torture_read_lock(void)
 617{
 618        preempt_disable();
 619        return 0;
 620}
 621
 622static void sched_torture_read_unlock(int idx)
 623{
 624        preempt_enable();
 625}
 626
 627static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 628{
 629        call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 630}
 631
 632static struct rcu_torture_ops sched_ops = {
 633        .init           = rcu_sync_torture_init,
 634        .readlock       = sched_torture_read_lock,
 635        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 636        .readunlock     = sched_torture_read_unlock,
 637        .completed      = rcu_no_completed,
 638        .deferred_free  = rcu_sched_torture_deferred_free,
 639        .sync           = synchronize_sched,
 640        .exp_sync       = synchronize_sched_expedited,
 641        .call           = call_rcu_sched,
 642        .cb_barrier     = rcu_barrier_sched,
 643        .fqs            = rcu_sched_force_quiescent_state,
 644        .stats          = NULL,
 645        .irq_capable    = 1,
 646        .name           = "sched"
 647};
 648
 649/*
 650 * RCU torture priority-boost testing.  Runs one real-time thread per
 651 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 652 * spinning waiting for them to be invoked.  If a given callback takes
 653 * too long to be invoked, we assume that priority inversion has occurred.
 654 */
 655
 656struct rcu_boost_inflight {
 657        struct rcu_head rcu;
 658        int inflight;
 659};
 660
 661static void rcu_torture_boost_cb(struct rcu_head *head)
 662{
 663        struct rcu_boost_inflight *rbip =
 664                container_of(head, struct rcu_boost_inflight, rcu);
 665
 666        smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 667        rbip->inflight = 0;
 668}
 669
 670static int rcu_torture_boost(void *arg)
 671{
 672        unsigned long call_rcu_time;
 673        unsigned long endtime;
 674        unsigned long oldstarttime;
 675        struct rcu_boost_inflight rbi = { .inflight = 0 };
 676        struct sched_param sp;
 677
 678        VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 679
 680        /* Set real-time priority. */
 681        sp.sched_priority = 1;
 682        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 683                VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 684                n_rcu_torture_boost_rterror++;
 685        }
 686
 687        init_rcu_head_on_stack(&rbi.rcu);
 688        /* Each pass through the following loop does one boost-test cycle. */
 689        do {
 690                /* Wait for the next test interval. */
 691                oldstarttime = boost_starttime;
 692                while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 693                        schedule_timeout_interruptible(oldstarttime - jiffies);
 694                        rcu_stutter_wait("rcu_torture_boost");
 695                        if (kthread_should_stop() ||
 696                            fullstop != FULLSTOP_DONTSTOP)
 697                                goto checkwait;
 698                }
 699
 700                /* Do one boost-test interval. */
 701                endtime = oldstarttime + test_boost_duration * HZ;
 702                call_rcu_time = jiffies;
 703                while (ULONG_CMP_LT(jiffies, endtime)) {
 704                        /* If we don't have a callback in flight, post one. */
 705                        if (!rbi.inflight) {
 706                                smp_mb(); /* RCU core before ->inflight = 1. */
 707                                rbi.inflight = 1;
 708                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 709                                if (jiffies - call_rcu_time >
 710                                         test_boost_duration * HZ - HZ / 2) {
 711                                        VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 712                                        n_rcu_torture_boost_failure++;
 713                                }
 714                                call_rcu_time = jiffies;
 715                        }
 716                        cond_resched();
 717                        rcu_stutter_wait("rcu_torture_boost");
 718                        if (kthread_should_stop() ||
 719                            fullstop != FULLSTOP_DONTSTOP)
 720                                goto checkwait;
 721                }
 722
 723                /*
 724                 * Set the start time of the next test interval.
 725                 * Yes, this is vulnerable to long delays, but such
 726                 * delays simply cause a false negative for the next
 727                 * interval.  Besides, we are running at RT priority,
 728                 * so delays should be relatively rare.
 729                 */
 730                while (oldstarttime == boost_starttime &&
 731                       !kthread_should_stop()) {
 732                        if (mutex_trylock(&boost_mutex)) {
 733                                boost_starttime = jiffies +
 734                                                  test_boost_interval * HZ;
 735                                n_rcu_torture_boosts++;
 736                                mutex_unlock(&boost_mutex);
 737                                break;
 738                        }
 739                        schedule_timeout_uninterruptible(1);
 740                }
 741
 742                /* Go do the stutter. */
 743checkwait:      rcu_stutter_wait("rcu_torture_boost");
 744        } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 745
 746        /* Clean up and exit. */
 747        VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 748        rcutorture_shutdown_absorb("rcu_torture_boost");
 749        while (!kthread_should_stop() || rbi.inflight)
 750                schedule_timeout_uninterruptible(1);
 751        smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 752        destroy_rcu_head_on_stack(&rbi.rcu);
 753        return 0;
 754}
 755
 756/*
 757 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 758 * bursts of calls to force_quiescent_state(), increasing the probability
 759 * of occurrence of some important types of race conditions.
 760 */
 761static int
 762rcu_torture_fqs(void *arg)
 763{
 764        unsigned long fqs_resume_time;
 765        int fqs_burst_remaining;
 766
 767        VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 768        do {
 769                fqs_resume_time = jiffies + fqs_stutter * HZ;
 770                while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 771                       !kthread_should_stop()) {
 772                        schedule_timeout_interruptible(1);
 773                }
 774                fqs_burst_remaining = fqs_duration;
 775                while (fqs_burst_remaining > 0 &&
 776                       !kthread_should_stop()) {
 777                        cur_ops->fqs();
 778                        udelay(fqs_holdoff);
 779                        fqs_burst_remaining -= fqs_holdoff;
 780                }
 781                rcu_stutter_wait("rcu_torture_fqs");
 782        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 783        VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 784        rcutorture_shutdown_absorb("rcu_torture_fqs");
 785        while (!kthread_should_stop())
 786                schedule_timeout_uninterruptible(1);
 787        return 0;
 788}
 789
 790/*
 791 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 792 * for that pointed to by rcu_torture_current, freeing the old structure
 793 * after a series of grace periods (the "pipeline").
 794 */
 795static int
 796rcu_torture_writer(void *arg)
 797{
 798        bool exp;
 799        int i;
 800        struct rcu_torture *rp;
 801        struct rcu_torture *rp1;
 802        struct rcu_torture *old_rp;
 803        static DEFINE_RCU_RANDOM(rand);
 804
 805        VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 806        set_user_nice(current, 19);
 807
 808        do {
 809                schedule_timeout_uninterruptible(1);
 810                rp = rcu_torture_alloc();
 811                if (rp == NULL)
 812                        continue;
 813                rp->rtort_pipe_count = 0;
 814                udelay(rcu_random(&rand) & 0x3ff);
 815                old_rp = rcu_dereference_check(rcu_torture_current,
 816                                               current == writer_task);
 817                rp->rtort_mbtest = 1;
 818                rcu_assign_pointer(rcu_torture_current, rp);
 819                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 820                if (old_rp) {
 821                        i = old_rp->rtort_pipe_count;
 822                        if (i > RCU_TORTURE_PIPE_LEN)
 823                                i = RCU_TORTURE_PIPE_LEN;
 824                        atomic_inc(&rcu_torture_wcount[i]);
 825                        old_rp->rtort_pipe_count++;
 826                        if (gp_normal == gp_exp)
 827                                exp = !!(rcu_random(&rand) & 0x80);
 828                        else
 829                                exp = gp_exp;
 830                        if (!exp) {
 831                                cur_ops->deferred_free(old_rp);
 832                        } else {
 833                                cur_ops->exp_sync();
 834                                list_add(&old_rp->rtort_free,
 835                                         &rcu_torture_removed);
 836                                list_for_each_entry_safe(rp, rp1,
 837                                                         &rcu_torture_removed,
 838                                                         rtort_free) {
 839                                        i = rp->rtort_pipe_count;
 840                                        if (i > RCU_TORTURE_PIPE_LEN)
 841                                                i = RCU_TORTURE_PIPE_LEN;
 842                                        atomic_inc(&rcu_torture_wcount[i]);
 843                                        if (++rp->rtort_pipe_count >=
 844                                            RCU_TORTURE_PIPE_LEN) {
 845                                                rp->rtort_mbtest = 0;
 846                                                list_del(&rp->rtort_free);
 847                                                rcu_torture_free(rp);
 848                                        }
 849                                 }
 850                        }
 851                }
 852                rcutorture_record_progress(++rcu_torture_current_version);
 853                rcu_stutter_wait("rcu_torture_writer");
 854        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 855        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 856        rcutorture_shutdown_absorb("rcu_torture_writer");
 857        while (!kthread_should_stop())
 858                schedule_timeout_uninterruptible(1);
 859        return 0;
 860}
 861
 862/*
 863 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 864 * delay between calls.
 865 */
 866static int
 867rcu_torture_fakewriter(void *arg)
 868{
 869        DEFINE_RCU_RANDOM(rand);
 870
 871        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 872        set_user_nice(current, 19);
 873
 874        do {
 875                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 876                udelay(rcu_random(&rand) & 0x3ff);
 877                if (cur_ops->cb_barrier != NULL &&
 878                    rcu_random(&rand) % (nfakewriters * 8) == 0) {
 879                        cur_ops->cb_barrier();
 880                } else if (gp_normal == gp_exp) {
 881                        if (rcu_random(&rand) & 0x80)
 882                                cur_ops->sync();
 883                        else
 884                                cur_ops->exp_sync();
 885                } else if (gp_normal) {
 886                        cur_ops->sync();
 887                } else {
 888                        cur_ops->exp_sync();
 889                }
 890                rcu_stutter_wait("rcu_torture_fakewriter");
 891        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 892
 893        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 894        rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 895        while (!kthread_should_stop())
 896                schedule_timeout_uninterruptible(1);
 897        return 0;
 898}
 899
 900void rcutorture_trace_dump(void)
 901{
 902        static atomic_t beenhere = ATOMIC_INIT(0);
 903
 904        if (atomic_read(&beenhere))
 905                return;
 906        if (atomic_xchg(&beenhere, 1) != 0)
 907                return;
 908        ftrace_dump(DUMP_ALL);
 909}
 910
 911/*
 912 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 913 * incrementing the corresponding element of the pipeline array.  The
 914 * counter in the element should never be greater than 1, otherwise, the
 915 * RCU implementation is broken.
 916 */
 917static void rcu_torture_timer(unsigned long unused)
 918{
 919        int idx;
 920        int completed;
 921        int completed_end;
 922        static DEFINE_RCU_RANDOM(rand);
 923        static DEFINE_SPINLOCK(rand_lock);
 924        struct rcu_torture *p;
 925        int pipe_count;
 926        unsigned long long ts;
 927
 928        idx = cur_ops->readlock();
 929        completed = cur_ops->completed();
 930        ts = rcu_trace_clock_local();
 931        p = rcu_dereference_check(rcu_torture_current,
 932                                  rcu_read_lock_bh_held() ||
 933                                  rcu_read_lock_sched_held() ||
 934                                  srcu_read_lock_held(&srcu_ctl));
 935        if (p == NULL) {
 936                /* Leave because rcu_torture_writer is not yet underway */
 937                cur_ops->readunlock(idx);
 938                return;
 939        }
 940        if (p->rtort_mbtest == 0)
 941                atomic_inc(&n_rcu_torture_mberror);
 942        spin_lock(&rand_lock);
 943        cur_ops->read_delay(&rand);
 944        n_rcu_torture_timers++;
 945        spin_unlock(&rand_lock);
 946        preempt_disable();
 947        pipe_count = p->rtort_pipe_count;
 948        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 949                /* Should not happen, but... */
 950                pipe_count = RCU_TORTURE_PIPE_LEN;
 951        }
 952        completed_end = cur_ops->completed();
 953        if (pipe_count > 1) {
 954                do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 955                                          completed, completed_end);
 956                rcutorture_trace_dump();
 957        }
 958        __this_cpu_inc(rcu_torture_count[pipe_count]);
 959        completed = completed_end - completed;
 960        if (completed > RCU_TORTURE_PIPE_LEN) {
 961                /* Should not happen, but... */
 962                completed = RCU_TORTURE_PIPE_LEN;
 963        }
 964        __this_cpu_inc(rcu_torture_batch[completed]);
 965        preempt_enable();
 966        cur_ops->readunlock(idx);
 967}
 968
 969/*
 970 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 971 * incrementing the corresponding element of the pipeline array.  The
 972 * counter in the element should never be greater than 1, otherwise, the
 973 * RCU implementation is broken.
 974 */
 975static int
 976rcu_torture_reader(void *arg)
 977{
 978        int completed;
 979        int completed_end;
 980        int idx;
 981        DEFINE_RCU_RANDOM(rand);
 982        struct rcu_torture *p;
 983        int pipe_count;
 984        struct timer_list t;
 985        unsigned long long ts;
 986
 987        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 988        set_user_nice(current, 19);
 989        if (irqreader && cur_ops->irq_capable)
 990                setup_timer_on_stack(&t, rcu_torture_timer, 0);
 991
 992        do {
 993                if (irqreader && cur_ops->irq_capable) {
 994                        if (!timer_pending(&t))
 995                                mod_timer(&t, jiffies + 1);
 996                }
 997                idx = cur_ops->readlock();
 998                completed = cur_ops->completed();
 999                ts = rcu_trace_clock_local();
1000                p = rcu_dereference_check(rcu_torture_current,
1001                                          rcu_read_lock_bh_held() ||
1002                                          rcu_read_lock_sched_held() ||
1003                                          srcu_read_lock_held(&srcu_ctl));
1004                if (p == NULL) {
1005                        /* Wait for rcu_torture_writer to get underway */
1006                        cur_ops->readunlock(idx);
1007                        schedule_timeout_interruptible(HZ);
1008                        continue;
1009                }
1010                if (p->rtort_mbtest == 0)
1011                        atomic_inc(&n_rcu_torture_mberror);
1012                cur_ops->read_delay(&rand);
1013                preempt_disable();
1014                pipe_count = p->rtort_pipe_count;
1015                if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1016                        /* Should not happen, but... */
1017                        pipe_count = RCU_TORTURE_PIPE_LEN;
1018                }
1019                completed_end = cur_ops->completed();
1020                if (pipe_count > 1) {
1021                        do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1022                                                  ts, completed, completed_end);
1023                        rcutorture_trace_dump();
1024                }
1025                __this_cpu_inc(rcu_torture_count[pipe_count]);
1026                completed = completed_end - completed;
1027                if (completed > RCU_TORTURE_PIPE_LEN) {
1028                        /* Should not happen, but... */
1029                        completed = RCU_TORTURE_PIPE_LEN;
1030                }
1031                __this_cpu_inc(rcu_torture_batch[completed]);
1032                preempt_enable();
1033                cur_ops->readunlock(idx);
1034                schedule();
1035                rcu_stutter_wait("rcu_torture_reader");
1036        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1037        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1038        rcutorture_shutdown_absorb("rcu_torture_reader");
1039        if (irqreader && cur_ops->irq_capable)
1040                del_timer_sync(&t);
1041        while (!kthread_should_stop())
1042                schedule_timeout_uninterruptible(1);
1043        return 0;
1044}
1045
1046/*
1047 * Create an RCU-torture statistics message in the specified buffer.
1048 */
1049static int
1050rcu_torture_printk(char *page)
1051{
1052        int cnt = 0;
1053        int cpu;
1054        int i;
1055        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1057
1058        for_each_possible_cpu(cpu) {
1059                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1060                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1061                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1062                }
1063        }
1064        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1065                if (pipesummary[i] != 0)
1066                        break;
1067        }
1068        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1069        cnt += sprintf(&page[cnt],
1070                       "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1071                       rcu_torture_current,
1072                       rcu_torture_current_version,
1073                       list_empty(&rcu_torture_freelist),
1074                       atomic_read(&n_rcu_torture_alloc),
1075                       atomic_read(&n_rcu_torture_alloc_fail),
1076                       atomic_read(&n_rcu_torture_free));
1077        cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1078                       atomic_read(&n_rcu_torture_mberror),
1079                       n_rcu_torture_boost_ktrerror,
1080                       n_rcu_torture_boost_rterror);
1081        cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1082                       n_rcu_torture_boost_failure,
1083                       n_rcu_torture_boosts,
1084                       n_rcu_torture_timers);
1085        cnt += sprintf(&page[cnt],
1086                       "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1087                       n_online_successes, n_online_attempts,
1088                       n_offline_successes, n_offline_attempts,
1089                       min_online, max_online,
1090                       min_offline, max_offline,
1091                       sum_online, sum_offline, HZ);
1092        cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1093                       n_barrier_successes,
1094                       n_barrier_attempts,
1095                       n_rcu_torture_barrier_error);
1096        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1097        if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1098            n_rcu_torture_barrier_error != 0 ||
1099            n_rcu_torture_boost_ktrerror != 0 ||
1100            n_rcu_torture_boost_rterror != 0 ||
1101            n_rcu_torture_boost_failure != 0 ||
1102            i > 1) {
1103                cnt += sprintf(&page[cnt], "!!! ");
1104                atomic_inc(&n_rcu_torture_error);
1105                WARN_ON_ONCE(1);
1106        }
1107        cnt += sprintf(&page[cnt], "Reader Pipe: ");
1108        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1109                cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1110        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1111        cnt += sprintf(&page[cnt], "Reader Batch: ");
1112        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1113                cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1114        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1115        cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1116        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1117                cnt += sprintf(&page[cnt], " %d",
1118                               atomic_read(&rcu_torture_wcount[i]));
1119        }
1120        cnt += sprintf(&page[cnt], "\n");
1121        if (cur_ops->stats)
1122                cnt += cur_ops->stats(&page[cnt]);
1123        return cnt;
1124}
1125
1126/*
1127 * Print torture statistics.  Caller must ensure that there is only
1128 * one call to this function at a given time!!!  This is normally
1129 * accomplished by relying on the module system to only have one copy
1130 * of the module loaded, and then by giving the rcu_torture_stats
1131 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1132 * thread is not running).
1133 */
1134static void
1135rcu_torture_stats_print(void)
1136{
1137        int cnt;
1138
1139        cnt = rcu_torture_printk(printk_buf);
1140        pr_alert("%s", printk_buf);
1141}
1142
1143/*
1144 * Periodically prints torture statistics, if periodic statistics printing
1145 * was specified via the stat_interval module parameter.
1146 *
1147 * No need to worry about fullstop here, since this one doesn't reference
1148 * volatile state or register callbacks.
1149 */
1150static int
1151rcu_torture_stats(void *arg)
1152{
1153        VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1154        do {
1155                schedule_timeout_interruptible(stat_interval * HZ);
1156                rcu_torture_stats_print();
1157                rcutorture_shutdown_absorb("rcu_torture_stats");
1158        } while (!kthread_should_stop());
1159        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1160        return 0;
1161}
1162
1163static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1164
1165/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1166 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1167 */
1168static void rcu_torture_shuffle_tasks(void)
1169{
1170        int i;
1171
1172        cpumask_setall(shuffle_tmp_mask);
1173        get_online_cpus();
1174
1175        /* No point in shuffling if there is only one online CPU (ex: UP) */
1176        if (num_online_cpus() == 1) {
1177                put_online_cpus();
1178                return;
1179        }
1180
1181        if (rcu_idle_cpu != -1)
1182                cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1183
1184        set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1185
1186        if (reader_tasks) {
1187                for (i = 0; i < nrealreaders; i++)
1188                        if (reader_tasks[i])
1189                                set_cpus_allowed_ptr(reader_tasks[i],
1190                                                     shuffle_tmp_mask);
1191        }
1192        if (fakewriter_tasks) {
1193                for (i = 0; i < nfakewriters; i++)
1194                        if (fakewriter_tasks[i])
1195                                set_cpus_allowed_ptr(fakewriter_tasks[i],
1196                                                     shuffle_tmp_mask);
1197        }
1198        if (writer_task)
1199                set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1200        if (stats_task)
1201                set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1202        if (stutter_task)
1203                set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1204        if (fqs_task)
1205                set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1206        if (shutdown_task)
1207                set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1208#ifdef CONFIG_HOTPLUG_CPU
1209        if (onoff_task)
1210                set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1211#endif /* #ifdef CONFIG_HOTPLUG_CPU */
1212        if (stall_task)
1213                set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1214        if (barrier_cbs_tasks)
1215                for (i = 0; i < n_barrier_cbs; i++)
1216                        if (barrier_cbs_tasks[i])
1217                                set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1218                                                     shuffle_tmp_mask);
1219        if (barrier_task)
1220                set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1221
1222        if (rcu_idle_cpu == -1)
1223                rcu_idle_cpu = num_online_cpus() - 1;
1224        else
1225                rcu_idle_cpu--;
1226
1227        put_online_cpus();
1228}
1229
1230/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1231 * system to become idle at a time and cut off its timer ticks. This is meant
1232 * to test the support for such tickless idle CPU in RCU.
1233 */
1234static int
1235rcu_torture_shuffle(void *arg)
1236{
1237        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1238        do {
1239                schedule_timeout_interruptible(shuffle_interval * HZ);
1240                rcu_torture_shuffle_tasks();
1241                rcutorture_shutdown_absorb("rcu_torture_shuffle");
1242        } while (!kthread_should_stop());
1243        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1244        return 0;
1245}
1246
1247/* Cause the rcutorture test to "stutter", starting and stopping all
1248 * threads periodically.
1249 */
1250static int
1251rcu_torture_stutter(void *arg)
1252{
1253        VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1254        do {
1255                schedule_timeout_interruptible(stutter * HZ);
1256                stutter_pause_test = 1;
1257                if (!kthread_should_stop())
1258                        schedule_timeout_interruptible(stutter * HZ);
1259                stutter_pause_test = 0;
1260                rcutorture_shutdown_absorb("rcu_torture_stutter");
1261        } while (!kthread_should_stop());
1262        VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1263        return 0;
1264}
1265
1266static inline void
1267rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1268{
1269        pr_alert("%s" TORTURE_FLAG
1270                 "--- %s: nreaders=%d nfakewriters=%d "
1271                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1272                 "shuffle_interval=%d stutter=%d irqreader=%d "
1273                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1274                 "test_boost=%d/%d test_boost_interval=%d "
1275                 "test_boost_duration=%d shutdown_secs=%d "
1276                 "stall_cpu=%d stall_cpu_holdoff=%d "
1277                 "n_barrier_cbs=%d "
1278                 "onoff_interval=%d onoff_holdoff=%d\n",
1279                 torture_type, tag, nrealreaders, nfakewriters,
1280                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1281                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1282                 test_boost, cur_ops->can_boost,
1283                 test_boost_interval, test_boost_duration, shutdown_secs,
1284                 stall_cpu, stall_cpu_holdoff,
1285                 n_barrier_cbs,
1286                 onoff_interval, onoff_holdoff);
1287}
1288
1289static struct notifier_block rcutorture_shutdown_nb = {
1290        .notifier_call = rcutorture_shutdown_notify,
1291};
1292
1293static void rcutorture_booster_cleanup(int cpu)
1294{
1295        struct task_struct *t;
1296
1297        if (boost_tasks[cpu] == NULL)
1298                return;
1299        mutex_lock(&boost_mutex);
1300        VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1301        t = boost_tasks[cpu];
1302        boost_tasks[cpu] = NULL;
1303        mutex_unlock(&boost_mutex);
1304
1305        /* This must be outside of the mutex, otherwise deadlock! */
1306        kthread_stop(t);
1307        boost_tasks[cpu] = NULL;
1308}
1309
1310static int rcutorture_booster_init(int cpu)
1311{
1312        int retval;
1313
1314        if (boost_tasks[cpu] != NULL)
1315                return 0;  /* Already created, nothing more to do. */
1316
1317        /* Don't allow time recalculation while creating a new task. */
1318        mutex_lock(&boost_mutex);
1319        VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1320        boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1321                                                  cpu_to_node(cpu),
1322                                                  "rcu_torture_boost");
1323        if (IS_ERR(boost_tasks[cpu])) {
1324                retval = PTR_ERR(boost_tasks[cpu]);
1325                VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1326                n_rcu_torture_boost_ktrerror++;
1327                boost_tasks[cpu] = NULL;
1328                mutex_unlock(&boost_mutex);
1329                return retval;
1330        }
1331        kthread_bind(boost_tasks[cpu], cpu);
1332        wake_up_process(boost_tasks[cpu]);
1333        mutex_unlock(&boost_mutex);
1334        return 0;
1335}
1336
1337/*
1338 * Cause the rcutorture test to shutdown the system after the test has
1339 * run for the time specified by the shutdown_secs module parameter.
1340 */
1341static int
1342rcu_torture_shutdown(void *arg)
1343{
1344        long delta;
1345        unsigned long jiffies_snap;
1346
1347        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1348        jiffies_snap = ACCESS_ONCE(jiffies);
1349        while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1350               !kthread_should_stop()) {
1351                delta = shutdown_time - jiffies_snap;
1352                if (verbose)
1353                        pr_alert("%s" TORTURE_FLAG
1354                                 "rcu_torture_shutdown task: %lu jiffies remaining\n",
1355                                 torture_type, delta);
1356                schedule_timeout_interruptible(delta);
1357                jiffies_snap = ACCESS_ONCE(jiffies);
1358        }
1359        if (kthread_should_stop()) {
1360                VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1361                return 0;
1362        }
1363
1364        /* OK, shut down the system. */
1365
1366        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1367        shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1368        rcu_torture_cleanup();  /* Get the success/failure message. */
1369        kernel_power_off();     /* Shut down the system. */
1370        return 0;
1371}
1372
1373#ifdef CONFIG_HOTPLUG_CPU
1374
1375/*
1376 * Execute random CPU-hotplug operations at the interval specified
1377 * by the onoff_interval.
1378 */
1379static int
1380rcu_torture_onoff(void *arg)
1381{
1382        int cpu;
1383        unsigned long delta;
1384        int maxcpu = -1;
1385        DEFINE_RCU_RANDOM(rand);
1386        int ret;
1387        unsigned long starttime;
1388
1389        VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1390        for_each_online_cpu(cpu)
1391                maxcpu = cpu;
1392        WARN_ON(maxcpu < 0);
1393        if (onoff_holdoff > 0) {
1394                VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1395                schedule_timeout_interruptible(onoff_holdoff * HZ);
1396                VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1397        }
1398        while (!kthread_should_stop()) {
1399                cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1400                if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1401                        if (verbose)
1402                                pr_alert("%s" TORTURE_FLAG
1403                                         "rcu_torture_onoff task: offlining %d\n",
1404                                         torture_type, cpu);
1405                        starttime = jiffies;
1406                        n_offline_attempts++;
1407                        ret = cpu_down(cpu);
1408                        if (ret) {
1409                                if (verbose)
1410                                        pr_alert("%s" TORTURE_FLAG
1411                                                 "rcu_torture_onoff task: offline %d failed: errno %d\n",
1412                                                 torture_type, cpu, ret);
1413                        } else {
1414                                if (verbose)
1415                                        pr_alert("%s" TORTURE_FLAG
1416                                                 "rcu_torture_onoff task: offlined %d\n",
1417                                                 torture_type, cpu);
1418                                n_offline_successes++;
1419                                delta = jiffies - starttime;
1420                                sum_offline += delta;
1421                                if (min_offline < 0) {
1422                                        min_offline = delta;
1423                                        max_offline = delta;
1424                                }
1425                                if (min_offline > delta)
1426                                        min_offline = delta;
1427                                if (max_offline < delta)
1428                                        max_offline = delta;
1429                        }
1430                } else if (cpu_is_hotpluggable(cpu)) {
1431                        if (verbose)
1432                                pr_alert("%s" TORTURE_FLAG
1433                                         "rcu_torture_onoff task: onlining %d\n",
1434                                         torture_type, cpu);
1435                        starttime = jiffies;
1436                        n_online_attempts++;
1437                        ret = cpu_up(cpu);
1438                        if (ret) {
1439                                if (verbose)
1440                                        pr_alert("%s" TORTURE_FLAG
1441                                                 "rcu_torture_onoff task: online %d failed: errno %d\n",
1442                                                 torture_type, cpu, ret);
1443                        } else {
1444                                if (verbose)
1445                                        pr_alert("%s" TORTURE_FLAG
1446                                                 "rcu_torture_onoff task: onlined %d\n",
1447                                                 torture_type, cpu);
1448                                n_online_successes++;
1449                                delta = jiffies - starttime;
1450                                sum_online += delta;
1451                                if (min_online < 0) {
1452                                        min_online = delta;
1453                                        max_online = delta;
1454                                }
1455                                if (min_online > delta)
1456                                        min_online = delta;
1457                                if (max_online < delta)
1458                                        max_online = delta;
1459                        }
1460                }
1461                schedule_timeout_interruptible(onoff_interval * HZ);
1462        }
1463        VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1464        return 0;
1465}
1466
1467static int
1468rcu_torture_onoff_init(void)
1469{
1470        int ret;
1471
1472        if (onoff_interval <= 0)
1473                return 0;
1474        onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1475        if (IS_ERR(onoff_task)) {
1476                ret = PTR_ERR(onoff_task);
1477                onoff_task = NULL;
1478                return ret;
1479        }
1480        return 0;
1481}
1482
1483static void rcu_torture_onoff_cleanup(void)
1484{
1485        if (onoff_task == NULL)
1486                return;
1487        VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1488        kthread_stop(onoff_task);
1489        onoff_task = NULL;
1490}
1491
1492#else /* #ifdef CONFIG_HOTPLUG_CPU */
1493
1494static int
1495rcu_torture_onoff_init(void)
1496{
1497        return 0;
1498}
1499
1500static void rcu_torture_onoff_cleanup(void)
1501{
1502}
1503
1504#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1505
1506/*
1507 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1508 * induces a CPU stall for the time specified by stall_cpu.
1509 */
1510static int rcu_torture_stall(void *args)
1511{
1512        unsigned long stop_at;
1513
1514        VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1515        if (stall_cpu_holdoff > 0) {
1516                VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1517                schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1518                VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1519        }
1520        if (!kthread_should_stop()) {
1521                stop_at = get_seconds() + stall_cpu;
1522                /* RCU CPU stall is expected behavior in following code. */
1523                pr_alert("rcu_torture_stall start.\n");
1524                rcu_read_lock();
1525                preempt_disable();
1526                while (ULONG_CMP_LT(get_seconds(), stop_at))
1527                        continue;  /* Induce RCU CPU stall warning. */
1528                preempt_enable();
1529                rcu_read_unlock();
1530                pr_alert("rcu_torture_stall end.\n");
1531        }
1532        rcutorture_shutdown_absorb("rcu_torture_stall");
1533        while (!kthread_should_stop())
1534                schedule_timeout_interruptible(10 * HZ);
1535        return 0;
1536}
1537
1538/* Spawn CPU-stall kthread, if stall_cpu specified. */
1539static int __init rcu_torture_stall_init(void)
1540{
1541        int ret;
1542
1543        if (stall_cpu <= 0)
1544                return 0;
1545        stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1546        if (IS_ERR(stall_task)) {
1547                ret = PTR_ERR(stall_task);
1548                stall_task = NULL;
1549                return ret;
1550        }
1551        return 0;
1552}
1553
1554/* Clean up after the CPU-stall kthread, if one was spawned. */
1555static void rcu_torture_stall_cleanup(void)
1556{
1557        if (stall_task == NULL)
1558                return;
1559        VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1560        kthread_stop(stall_task);
1561        stall_task = NULL;
1562}
1563
1564/* Callback function for RCU barrier testing. */
1565void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1566{
1567        atomic_inc(&barrier_cbs_invoked);
1568}
1569
1570/* kthread function to register callbacks used to test RCU barriers. */
1571static int rcu_torture_barrier_cbs(void *arg)
1572{
1573        long myid = (long)arg;
1574        bool lastphase = 0;
1575        struct rcu_head rcu;
1576
1577        init_rcu_head_on_stack(&rcu);
1578        VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1579        set_user_nice(current, 19);
1580        do {
1581                wait_event(barrier_cbs_wq[myid],
1582                           barrier_phase != lastphase ||
1583                           kthread_should_stop() ||
1584                           fullstop != FULLSTOP_DONTSTOP);
1585                lastphase = barrier_phase;
1586                smp_mb(); /* ensure barrier_phase load before ->call(). */
1587                if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1588                        break;
1589                cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1590                if (atomic_dec_and_test(&barrier_cbs_count))
1591                        wake_up(&barrier_wq);
1592        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1593        VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1594        rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1595        while (!kthread_should_stop())
1596                schedule_timeout_interruptible(1);
1597        cur_ops->cb_barrier();
1598        destroy_rcu_head_on_stack(&rcu);
1599        return 0;
1600}
1601
1602/* kthread function to drive and coordinate RCU barrier testing. */
1603static int rcu_torture_barrier(void *arg)
1604{
1605        int i;
1606
1607        VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1608        do {
1609                atomic_set(&barrier_cbs_invoked, 0);
1610                atomic_set(&barrier_cbs_count, n_barrier_cbs);
1611                smp_mb(); /* Ensure barrier_phase after prior assignments. */
1612                barrier_phase = !barrier_phase;
1613                for (i = 0; i < n_barrier_cbs; i++)
1614                        wake_up(&barrier_cbs_wq[i]);
1615                wait_event(barrier_wq,
1616                           atomic_read(&barrier_cbs_count) == 0 ||
1617                           kthread_should_stop() ||
1618                           fullstop != FULLSTOP_DONTSTOP);
1619                if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1620                        break;
1621                n_barrier_attempts++;
1622                cur_ops->cb_barrier();
1623                if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1624                        n_rcu_torture_barrier_error++;
1625                        WARN_ON_ONCE(1);
1626                }
1627                n_barrier_successes++;
1628                schedule_timeout_interruptible(HZ / 10);
1629        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1630        VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1631        rcutorture_shutdown_absorb("rcu_torture_barrier");
1632        while (!kthread_should_stop())
1633                schedule_timeout_interruptible(1);
1634        return 0;
1635}
1636
1637/* Initialize RCU barrier testing. */
1638static int rcu_torture_barrier_init(void)
1639{
1640        int i;
1641        int ret;
1642
1643        if (n_barrier_cbs == 0)
1644                return 0;
1645        if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1646                pr_alert("%s" TORTURE_FLAG
1647                         " Call or barrier ops missing for %s,\n",
1648                         torture_type, cur_ops->name);
1649                pr_alert("%s" TORTURE_FLAG
1650                         " RCU barrier testing omitted from run.\n",
1651                         torture_type);
1652                return 0;
1653        }
1654        atomic_set(&barrier_cbs_count, 0);
1655        atomic_set(&barrier_cbs_invoked, 0);
1656        barrier_cbs_tasks =
1657                kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1658                        GFP_KERNEL);
1659        barrier_cbs_wq =
1660                kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1661                        GFP_KERNEL);
1662        if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1663                return -ENOMEM;
1664        for (i = 0; i < n_barrier_cbs; i++) {
1665                init_waitqueue_head(&barrier_cbs_wq[i]);
1666                barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1667                                                   (void *)(long)i,
1668                                                   "rcu_torture_barrier_cbs");
1669                if (IS_ERR(barrier_cbs_tasks[i])) {
1670                        ret = PTR_ERR(barrier_cbs_tasks[i]);
1671                        VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1672                        barrier_cbs_tasks[i] = NULL;
1673                        return ret;
1674                }
1675        }
1676        barrier_task = kthread_run(rcu_torture_barrier, NULL,
1677                                   "rcu_torture_barrier");
1678        if (IS_ERR(barrier_task)) {
1679                ret = PTR_ERR(barrier_task);
1680                VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1681                barrier_task = NULL;
1682        }
1683        return 0;
1684}
1685
1686/* Clean up after RCU barrier testing. */
1687static void rcu_torture_barrier_cleanup(void)
1688{
1689        int i;
1690
1691        if (barrier_task != NULL) {
1692                VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1693                kthread_stop(barrier_task);
1694                barrier_task = NULL;
1695        }
1696        if (barrier_cbs_tasks != NULL) {
1697                for (i = 0; i < n_barrier_cbs; i++) {
1698                        if (barrier_cbs_tasks[i] != NULL) {
1699                                VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1700                                kthread_stop(barrier_cbs_tasks[i]);
1701                                barrier_cbs_tasks[i] = NULL;
1702                        }
1703                }
1704                kfree(barrier_cbs_tasks);
1705                barrier_cbs_tasks = NULL;
1706        }
1707        if (barrier_cbs_wq != NULL) {
1708                kfree(barrier_cbs_wq);
1709                barrier_cbs_wq = NULL;
1710        }
1711}
1712
1713static int rcutorture_cpu_notify(struct notifier_block *self,
1714                                 unsigned long action, void *hcpu)
1715{
1716        long cpu = (long)hcpu;
1717
1718        switch (action) {
1719        case CPU_ONLINE:
1720        case CPU_DOWN_FAILED:
1721                (void)rcutorture_booster_init(cpu);
1722                break;
1723        case CPU_DOWN_PREPARE:
1724                rcutorture_booster_cleanup(cpu);
1725                break;
1726        default:
1727                break;
1728        }
1729        return NOTIFY_OK;
1730}
1731
1732static struct notifier_block rcutorture_cpu_nb = {
1733        .notifier_call = rcutorture_cpu_notify,
1734};
1735
1736static void
1737rcu_torture_cleanup(void)
1738{
1739        int i;
1740
1741        mutex_lock(&fullstop_mutex);
1742        rcutorture_record_test_transition();
1743        if (fullstop == FULLSTOP_SHUTDOWN) {
1744                pr_warn(/* but going down anyway, so... */
1745                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1746                mutex_unlock(&fullstop_mutex);
1747                schedule_timeout_uninterruptible(10);
1748                if (cur_ops->cb_barrier != NULL)
1749                        cur_ops->cb_barrier();
1750                return;
1751        }
1752        fullstop = FULLSTOP_RMMOD;
1753        mutex_unlock(&fullstop_mutex);
1754        unregister_reboot_notifier(&rcutorture_shutdown_nb);
1755        rcu_torture_barrier_cleanup();
1756        rcu_torture_stall_cleanup();
1757        if (stutter_task) {
1758                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1759                kthread_stop(stutter_task);
1760        }
1761        stutter_task = NULL;
1762        if (shuffler_task) {
1763                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1764                kthread_stop(shuffler_task);
1765                free_cpumask_var(shuffle_tmp_mask);
1766        }
1767        shuffler_task = NULL;
1768
1769        if (writer_task) {
1770                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1771                kthread_stop(writer_task);
1772        }
1773        writer_task = NULL;
1774
1775        if (reader_tasks) {
1776                for (i = 0; i < nrealreaders; i++) {
1777                        if (reader_tasks[i]) {
1778                                VERBOSE_PRINTK_STRING(
1779                                        "Stopping rcu_torture_reader task");
1780                                kthread_stop(reader_tasks[i]);
1781                        }
1782                        reader_tasks[i] = NULL;
1783                }
1784                kfree(reader_tasks);
1785                reader_tasks = NULL;
1786        }
1787        rcu_torture_current = NULL;
1788
1789        if (fakewriter_tasks) {
1790                for (i = 0; i < nfakewriters; i++) {
1791                        if (fakewriter_tasks[i]) {
1792                                VERBOSE_PRINTK_STRING(
1793                                        "Stopping rcu_torture_fakewriter task");
1794                                kthread_stop(fakewriter_tasks[i]);
1795                        }
1796                        fakewriter_tasks[i] = NULL;
1797                }
1798                kfree(fakewriter_tasks);
1799                fakewriter_tasks = NULL;
1800        }
1801
1802        if (stats_task) {
1803                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1804                kthread_stop(stats_task);
1805        }
1806        stats_task = NULL;
1807
1808        if (fqs_task) {
1809                VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1810                kthread_stop(fqs_task);
1811        }
1812        fqs_task = NULL;
1813        if ((test_boost == 1 && cur_ops->can_boost) ||
1814            test_boost == 2) {
1815                unregister_cpu_notifier(&rcutorture_cpu_nb);
1816                for_each_possible_cpu(i)
1817                        rcutorture_booster_cleanup(i);
1818        }
1819        if (shutdown_task != NULL) {
1820                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1821                kthread_stop(shutdown_task);
1822        }
1823        shutdown_task = NULL;
1824        rcu_torture_onoff_cleanup();
1825
1826        /* Wait for all RCU callbacks to fire.  */
1827
1828        if (cur_ops->cb_barrier != NULL)
1829                cur_ops->cb_barrier();
1830
1831        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1832
1833        if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1834                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1835        else if (n_online_successes != n_online_attempts ||
1836                 n_offline_successes != n_offline_attempts)
1837                rcu_torture_print_module_parms(cur_ops,
1838                                               "End of test: RCU_HOTPLUG");
1839        else
1840                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1841}
1842
1843#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1844static void rcu_torture_leak_cb(struct rcu_head *rhp)
1845{
1846}
1847
1848static void rcu_torture_err_cb(struct rcu_head *rhp)
1849{
1850        /*
1851         * This -might- happen due to race conditions, but is unlikely.
1852         * The scenario that leads to this happening is that the
1853         * first of the pair of duplicate callbacks is queued,
1854         * someone else starts a grace period that includes that
1855         * callback, then the second of the pair must wait for the
1856         * next grace period.  Unlikely, but can happen.  If it
1857         * does happen, the debug-objects subsystem won't have splatted.
1858         */
1859        pr_alert("rcutorture: duplicated callback was invoked.\n");
1860}
1861#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1862
1863/*
1864 * Verify that double-free causes debug-objects to complain, but only
1865 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1866 * cannot be carried out.
1867 */
1868static void rcu_test_debug_objects(void)
1869{
1870#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1871        struct rcu_head rh1;
1872        struct rcu_head rh2;
1873
1874        init_rcu_head_on_stack(&rh1);
1875        init_rcu_head_on_stack(&rh2);
1876        pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1877
1878        /* Try to queue the rh2 pair of callbacks for the same grace period. */
1879        preempt_disable(); /* Prevent preemption from interrupting test. */
1880        rcu_read_lock(); /* Make it impossible to finish a grace period. */
1881        call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1882        local_irq_disable(); /* Make it harder to start a new grace period. */
1883        call_rcu(&rh2, rcu_torture_leak_cb);
1884        call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1885        local_irq_enable();
1886        rcu_read_unlock();
1887        preempt_enable();
1888
1889        /* Wait for them all to get done so we can safely return. */
1890        rcu_barrier();
1891        pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1892        destroy_rcu_head_on_stack(&rh1);
1893        destroy_rcu_head_on_stack(&rh2);
1894#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1895        pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1896#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1897}
1898
1899static int __init
1900rcu_torture_init(void)
1901{
1902        int i;
1903        int cpu;
1904        int firsterr = 0;
1905        int retval;
1906        static struct rcu_torture_ops *torture_ops[] = {
1907                &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1908        };
1909
1910        mutex_lock(&fullstop_mutex);
1911
1912        /* Process args and tell the world that the torturer is on the job. */
1913        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1914                cur_ops = torture_ops[i];
1915                if (strcmp(torture_type, cur_ops->name) == 0)
1916                        break;
1917        }
1918        if (i == ARRAY_SIZE(torture_ops)) {
1919                pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1920                         torture_type);
1921                pr_alert("rcu-torture types:");
1922                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1923                        pr_alert(" %s", torture_ops[i]->name);
1924                pr_alert("\n");
1925                mutex_unlock(&fullstop_mutex);
1926                return -EINVAL;
1927        }
1928        if (cur_ops->fqs == NULL && fqs_duration != 0) {
1929                pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1930                fqs_duration = 0;
1931        }
1932        if (cur_ops->init)
1933                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1934
1935        if (nreaders >= 0)
1936                nrealreaders = nreaders;
1937        else
1938                nrealreaders = 2 * num_online_cpus();
1939        rcu_torture_print_module_parms(cur_ops, "Start of test");
1940        fullstop = FULLSTOP_DONTSTOP;
1941
1942        /* Set up the freelist. */
1943
1944        INIT_LIST_HEAD(&rcu_torture_freelist);
1945        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1946                rcu_tortures[i].rtort_mbtest = 0;
1947                list_add_tail(&rcu_tortures[i].rtort_free,
1948                              &rcu_torture_freelist);
1949        }
1950
1951        /* Initialize the statistics so that each run gets its own numbers. */
1952
1953        rcu_torture_current = NULL;
1954        rcu_torture_current_version = 0;
1955        atomic_set(&n_rcu_torture_alloc, 0);
1956        atomic_set(&n_rcu_torture_alloc_fail, 0);
1957        atomic_set(&n_rcu_torture_free, 0);
1958        atomic_set(&n_rcu_torture_mberror, 0);
1959        atomic_set(&n_rcu_torture_error, 0);
1960        n_rcu_torture_barrier_error = 0;
1961        n_rcu_torture_boost_ktrerror = 0;
1962        n_rcu_torture_boost_rterror = 0;
1963        n_rcu_torture_boost_failure = 0;
1964        n_rcu_torture_boosts = 0;
1965        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1966                atomic_set(&rcu_torture_wcount[i], 0);
1967        for_each_possible_cpu(cpu) {
1968                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1969                        per_cpu(rcu_torture_count, cpu)[i] = 0;
1970                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
1971                }
1972        }
1973
1974        /* Start up the kthreads. */
1975
1976        VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1977        writer_task = kthread_create(rcu_torture_writer, NULL,
1978                                     "rcu_torture_writer");
1979        if (IS_ERR(writer_task)) {
1980                firsterr = PTR_ERR(writer_task);
1981                VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1982                writer_task = NULL;
1983                goto unwind;
1984        }
1985        wake_up_process(writer_task);
1986        fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1987                                   GFP_KERNEL);
1988        if (fakewriter_tasks == NULL) {
1989                VERBOSE_PRINTK_ERRSTRING("out of memory");
1990                firsterr = -ENOMEM;
1991                goto unwind;
1992        }
1993        for (i = 0; i < nfakewriters; i++) {
1994                VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1995                fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1996                                                  "rcu_torture_fakewriter");
1997                if (IS_ERR(fakewriter_tasks[i])) {
1998                        firsterr = PTR_ERR(fakewriter_tasks[i]);
1999                        VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2000                        fakewriter_tasks[i] = NULL;
2001                        goto unwind;
2002                }
2003        }
2004        reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2005                               GFP_KERNEL);
2006        if (reader_tasks == NULL) {
2007                VERBOSE_PRINTK_ERRSTRING("out of memory");
2008                firsterr = -ENOMEM;
2009                goto unwind;
2010        }
2011        for (i = 0; i < nrealreaders; i++) {
2012                VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2013                reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2014                                              "rcu_torture_reader");
2015                if (IS_ERR(reader_tasks[i])) {
2016                        firsterr = PTR_ERR(reader_tasks[i]);
2017                        VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2018                        reader_tasks[i] = NULL;
2019                        goto unwind;
2020                }
2021        }
2022        if (stat_interval > 0) {
2023                VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2024                stats_task = kthread_run(rcu_torture_stats, NULL,
2025                                        "rcu_torture_stats");
2026                if (IS_ERR(stats_task)) {
2027                        firsterr = PTR_ERR(stats_task);
2028                        VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2029                        stats_task = NULL;
2030                        goto unwind;
2031                }
2032        }
2033        if (test_no_idle_hz) {
2034                rcu_idle_cpu = num_online_cpus() - 1;
2035
2036                if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2037                        firsterr = -ENOMEM;
2038                        VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2039                        goto unwind;
2040                }
2041
2042                /* Create the shuffler thread */
2043                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2044                                          "rcu_torture_shuffle");
2045                if (IS_ERR(shuffler_task)) {
2046                        free_cpumask_var(shuffle_tmp_mask);
2047                        firsterr = PTR_ERR(shuffler_task);
2048                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2049                        shuffler_task = NULL;
2050                        goto unwind;
2051                }
2052        }
2053        if (stutter < 0)
2054                stutter = 0;
2055        if (stutter) {
2056                /* Create the stutter thread */
2057                stutter_task = kthread_run(rcu_torture_stutter, NULL,
2058                                          "rcu_torture_stutter");
2059                if (IS_ERR(stutter_task)) {
2060                        firsterr = PTR_ERR(stutter_task);
2061                        VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2062                        stutter_task = NULL;
2063                        goto unwind;
2064                }
2065        }
2066        if (fqs_duration < 0)
2067                fqs_duration = 0;
2068        if (fqs_duration) {
2069                /* Create the stutter thread */
2070                fqs_task = kthread_run(rcu_torture_fqs, NULL,
2071                                       "rcu_torture_fqs");
2072                if (IS_ERR(fqs_task)) {
2073                        firsterr = PTR_ERR(fqs_task);
2074                        VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2075                        fqs_task = NULL;
2076                        goto unwind;
2077                }
2078        }
2079        if (test_boost_interval < 1)
2080                test_boost_interval = 1;
2081        if (test_boost_duration < 2)
2082                test_boost_duration = 2;
2083        if ((test_boost == 1 && cur_ops->can_boost) ||
2084            test_boost == 2) {
2085
2086                boost_starttime = jiffies + test_boost_interval * HZ;
2087                register_cpu_notifier(&rcutorture_cpu_nb);
2088                for_each_possible_cpu(i) {
2089                        if (cpu_is_offline(i))
2090                                continue;  /* Heuristic: CPU can go offline. */
2091                        retval = rcutorture_booster_init(i);
2092                        if (retval < 0) {
2093                                firsterr = retval;
2094                                goto unwind;
2095                        }
2096                }
2097        }
2098        if (shutdown_secs > 0) {
2099                shutdown_time = jiffies + shutdown_secs * HZ;
2100                shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2101                                               "rcu_torture_shutdown");
2102                if (IS_ERR(shutdown_task)) {
2103                        firsterr = PTR_ERR(shutdown_task);
2104                        VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2105                        shutdown_task = NULL;
2106                        goto unwind;
2107                }
2108                wake_up_process(shutdown_task);
2109        }
2110        i = rcu_torture_onoff_init();
2111        if (i != 0) {
2112                firsterr = i;
2113                goto unwind;
2114        }
2115        register_reboot_notifier(&rcutorture_shutdown_nb);
2116        i = rcu_torture_stall_init();
2117        if (i != 0) {
2118                firsterr = i;
2119                goto unwind;
2120        }
2121        retval = rcu_torture_barrier_init();
2122        if (retval != 0) {
2123                firsterr = retval;
2124                goto unwind;
2125        }
2126        if (object_debug)
2127                rcu_test_debug_objects();
2128        rcutorture_record_test_transition();
2129        mutex_unlock(&fullstop_mutex);
2130        return 0;
2131
2132unwind:
2133        mutex_unlock(&fullstop_mutex);
2134        rcu_torture_cleanup();
2135        return firsterr;
2136}
2137
2138module_init(rcu_torture_init);
2139module_exit(rcu_torture_cleanup);
2140
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