linux/kernel/rcu/rcutorture.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Read-Copy Update module-based torture test facility
   4 *
   5 * Copyright (C) IBM Corporation, 2005, 2006
   6 *
   7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8 *        Josh Triplett <josh@joshtriplett.org>
   9 *
  10 * See also:  Documentation/RCU/torture.txt
  11 */
  12
  13#define pr_fmt(fmt) fmt
  14
  15#include <linux/types.h>
  16#include <linux/kernel.h>
  17#include <linux/init.h>
  18#include <linux/module.h>
  19#include <linux/kthread.h>
  20#include <linux/err.h>
  21#include <linux/spinlock.h>
  22#include <linux/smp.h>
  23#include <linux/rcupdate.h>
  24#include <linux/interrupt.h>
  25#include <linux/sched/signal.h>
  26#include <uapi/linux/sched/types.h>
  27#include <linux/atomic.h>
  28#include <linux/bitops.h>
  29#include <linux/completion.h>
  30#include <linux/moduleparam.h>
  31#include <linux/percpu.h>
  32#include <linux/notifier.h>
  33#include <linux/reboot.h>
  34#include <linux/freezer.h>
  35#include <linux/cpu.h>
  36#include <linux/delay.h>
  37#include <linux/stat.h>
  38#include <linux/srcu.h>
  39#include <linux/slab.h>
  40#include <linux/trace_clock.h>
  41#include <asm/byteorder.h>
  42#include <linux/torture.h>
  43#include <linux/vmalloc.h>
  44#include <linux/sched/debug.h>
  45#include <linux/sched/sysctl.h>
  46#include <linux/oom.h>
  47
  48#include "rcu.h"
  49
  50MODULE_LICENSE("GPL");
  51MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  52
  53
  54/* Bits for ->extendables field, extendables param, and related definitions. */
  55#define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  56#define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  57#define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  58#define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  59#define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  60#define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  61#define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  62#define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  63#define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  64#define RCUTORTURE_MAX_EXTEND    \
  65        (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  66         RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  67#define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  68                                        /* Must be power of two minus one. */
  69#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  70
  71torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  72              "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  73torture_param(int, fqs_duration, 0,
  74              "Duration of fqs bursts (us), 0 to disable");
  75torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  76torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  77torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  78torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  79torture_param(int, fwd_progress_holdoff, 60,
  80              "Time between forward-progress tests (s)");
  81torture_param(bool, fwd_progress_need_resched, 1,
  82              "Hide cond_resched() behind need_resched()");
  83torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  84torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  85torture_param(bool, gp_normal, false,
  86             "Use normal (non-expedited) GP wait primitives");
  87torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  88torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  89torture_param(int, n_barrier_cbs, 0,
  90             "# of callbacks/kthreads for barrier testing");
  91torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  92torture_param(int, nreaders, -1, "Number of RCU reader threads");
  93torture_param(int, object_debug, 0,
  94             "Enable debug-object double call_rcu() testing");
  95torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  96torture_param(int, onoff_interval, 0,
  97             "Time between CPU hotplugs (jiffies), 0=disable");
  98torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  99torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 100torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 101torture_param(int, stall_cpu_holdoff, 10,
 102             "Time to wait before starting stall (s).");
 103torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 104torture_param(int, stat_interval, 60,
 105             "Number of seconds between stats printk()s");
 106torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 107torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 108torture_param(int, test_boost_duration, 4,
 109             "Duration of each boost test, seconds.");
 110torture_param(int, test_boost_interval, 7,
 111             "Interval between boost tests, seconds.");
 112torture_param(bool, test_no_idle_hz, true,
 113             "Test support for tickless idle CPUs");
 114torture_param(int, verbose, 1,
 115             "Enable verbose debugging printk()s");
 116
 117static char *torture_type = "rcu";
 118module_param(torture_type, charp, 0444);
 119MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 120
 121static int nrealreaders;
 122static struct task_struct *writer_task;
 123static struct task_struct **fakewriter_tasks;
 124static struct task_struct **reader_tasks;
 125static struct task_struct *stats_task;
 126static struct task_struct *fqs_task;
 127static struct task_struct *boost_tasks[NR_CPUS];
 128static struct task_struct *stall_task;
 129static struct task_struct *fwd_prog_task;
 130static struct task_struct **barrier_cbs_tasks;
 131static struct task_struct *barrier_task;
 132
 133#define RCU_TORTURE_PIPE_LEN 10
 134
 135struct rcu_torture {
 136        struct rcu_head rtort_rcu;
 137        int rtort_pipe_count;
 138        struct list_head rtort_free;
 139        int rtort_mbtest;
 140};
 141
 142static LIST_HEAD(rcu_torture_freelist);
 143static struct rcu_torture __rcu *rcu_torture_current;
 144static unsigned long rcu_torture_current_version;
 145static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 146static DEFINE_SPINLOCK(rcu_torture_lock);
 147static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 148static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 149static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 150static atomic_t n_rcu_torture_alloc;
 151static atomic_t n_rcu_torture_alloc_fail;
 152static atomic_t n_rcu_torture_free;
 153static atomic_t n_rcu_torture_mberror;
 154static atomic_t n_rcu_torture_error;
 155static long n_rcu_torture_barrier_error;
 156static long n_rcu_torture_boost_ktrerror;
 157static long n_rcu_torture_boost_rterror;
 158static long n_rcu_torture_boost_failure;
 159static long n_rcu_torture_boosts;
 160static atomic_long_t n_rcu_torture_timers;
 161static long n_barrier_attempts;
 162static long n_barrier_successes; /* did rcu_barrier test succeed? */
 163static struct list_head rcu_torture_removed;
 164static unsigned long shutdown_jiffies;
 165
 166static int rcu_torture_writer_state;
 167#define RTWS_FIXED_DELAY        0
 168#define RTWS_DELAY              1
 169#define RTWS_REPLACE            2
 170#define RTWS_DEF_FREE           3
 171#define RTWS_EXP_SYNC           4
 172#define RTWS_COND_GET           5
 173#define RTWS_COND_SYNC          6
 174#define RTWS_SYNC               7
 175#define RTWS_STUTTER            8
 176#define RTWS_STOPPING           9
 177static const char * const rcu_torture_writer_state_names[] = {
 178        "RTWS_FIXED_DELAY",
 179        "RTWS_DELAY",
 180        "RTWS_REPLACE",
 181        "RTWS_DEF_FREE",
 182        "RTWS_EXP_SYNC",
 183        "RTWS_COND_GET",
 184        "RTWS_COND_SYNC",
 185        "RTWS_SYNC",
 186        "RTWS_STUTTER",
 187        "RTWS_STOPPING",
 188};
 189
 190/* Record reader segment types and duration for first failing read. */
 191struct rt_read_seg {
 192        int rt_readstate;
 193        unsigned long rt_delay_jiffies;
 194        unsigned long rt_delay_ms;
 195        unsigned long rt_delay_us;
 196        bool rt_preempted;
 197};
 198static int err_segs_recorded;
 199static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 200static int rt_read_nsegs;
 201
 202static const char *rcu_torture_writer_state_getname(void)
 203{
 204        unsigned int i = READ_ONCE(rcu_torture_writer_state);
 205
 206        if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 207                return "???";
 208        return rcu_torture_writer_state_names[i];
 209}
 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
 222        (void)do_div(ts, NSEC_PER_USEC);
 223        return ts;
 224}
 225#else /* #ifdef CONFIG_RCU_TRACE */
 226static u64 notrace rcu_trace_clock_local(void)
 227{
 228        return 0ULL;
 229}
 230#endif /* #else #ifdef CONFIG_RCU_TRACE */
 231
 232/*
 233 * Stop aggressive CPU-hog tests a bit before the end of the test in order
 234 * to avoid interfering with test shutdown.
 235 */
 236static bool shutdown_time_arrived(void)
 237{
 238        return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 239}
 240
 241static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 242static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 243                                        /*  and boost task create/destroy. */
 244static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 245static bool barrier_phase;              /* Test phase. */
 246static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 247static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 248static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 249
 250static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 251
 252/*
 253 * Allocate an element from the rcu_tortures pool.
 254 */
 255static struct rcu_torture *
 256rcu_torture_alloc(void)
 257{
 258        struct list_head *p;
 259
 260        spin_lock_bh(&rcu_torture_lock);
 261        if (list_empty(&rcu_torture_freelist)) {
 262                atomic_inc(&n_rcu_torture_alloc_fail);
 263                spin_unlock_bh(&rcu_torture_lock);
 264                return NULL;
 265        }
 266        atomic_inc(&n_rcu_torture_alloc);
 267        p = rcu_torture_freelist.next;
 268        list_del_init(p);
 269        spin_unlock_bh(&rcu_torture_lock);
 270        return container_of(p, struct rcu_torture, rtort_free);
 271}
 272
 273/*
 274 * Free an element to the rcu_tortures pool.
 275 */
 276static void
 277rcu_torture_free(struct rcu_torture *p)
 278{
 279        atomic_inc(&n_rcu_torture_free);
 280        spin_lock_bh(&rcu_torture_lock);
 281        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 282        spin_unlock_bh(&rcu_torture_lock);
 283}
 284
 285/*
 286 * Operations vector for selecting different types of tests.
 287 */
 288
 289struct rcu_torture_ops {
 290        int ttype;
 291        void (*init)(void);
 292        void (*cleanup)(void);
 293        int (*readlock)(void);
 294        void (*read_delay)(struct torture_random_state *rrsp,
 295                           struct rt_read_seg *rtrsp);
 296        void (*readunlock)(int idx);
 297        unsigned long (*get_gp_seq)(void);
 298        unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 299        void (*deferred_free)(struct rcu_torture *p);
 300        void (*sync)(void);
 301        void (*exp_sync)(void);
 302        unsigned long (*get_state)(void);
 303        void (*cond_sync)(unsigned long oldstate);
 304        call_rcu_func_t call;
 305        void (*cb_barrier)(void);
 306        void (*fqs)(void);
 307        void (*stats)(void);
 308        int (*stall_dur)(void);
 309        int irq_capable;
 310        int can_boost;
 311        int extendables;
 312        int slow_gps;
 313        const char *name;
 314};
 315
 316static struct rcu_torture_ops *cur_ops;
 317
 318/*
 319 * Definitions for rcu torture testing.
 320 */
 321
 322static int rcu_torture_read_lock(void) __acquires(RCU)
 323{
 324        rcu_read_lock();
 325        return 0;
 326}
 327
 328static void
 329rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 330{
 331        unsigned long started;
 332        unsigned long completed;
 333        const unsigned long shortdelay_us = 200;
 334        unsigned long longdelay_ms = 300;
 335        unsigned long long ts;
 336
 337        /* We want a short delay sometimes to make a reader delay the grace
 338         * period, and we want a long delay occasionally to trigger
 339         * force_quiescent_state. */
 340
 341        if (!rcu_fwd_cb_nodelay &&
 342            !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 343                started = cur_ops->get_gp_seq();
 344                ts = rcu_trace_clock_local();
 345                if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 346                        longdelay_ms = 5; /* Avoid triggering BH limits. */
 347                mdelay(longdelay_ms);
 348                rtrsp->rt_delay_ms = longdelay_ms;
 349                completed = cur_ops->get_gp_seq();
 350                do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 351                                          started, completed);
 352        }
 353        if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 354                udelay(shortdelay_us);
 355                rtrsp->rt_delay_us = shortdelay_us;
 356        }
 357        if (!preempt_count() &&
 358            !(torture_random(rrsp) % (nrealreaders * 500))) {
 359                torture_preempt_schedule();  /* QS only if preemptible. */
 360                rtrsp->rt_preempted = true;
 361        }
 362}
 363
 364static void rcu_torture_read_unlock(int idx) __releases(RCU)
 365{
 366        rcu_read_unlock();
 367}
 368
 369/*
 370 * Update callback in the pipe.  This should be invoked after a grace period.
 371 */
 372static bool
 373rcu_torture_pipe_update_one(struct rcu_torture *rp)
 374{
 375        int i;
 376
 377        i = rp->rtort_pipe_count;
 378        if (i > RCU_TORTURE_PIPE_LEN)
 379                i = RCU_TORTURE_PIPE_LEN;
 380        atomic_inc(&rcu_torture_wcount[i]);
 381        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 382                rp->rtort_mbtest = 0;
 383                return true;
 384        }
 385        return false;
 386}
 387
 388/*
 389 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 390 * primitives.
 391 */
 392static void
 393rcu_torture_pipe_update(struct rcu_torture *old_rp)
 394{
 395        struct rcu_torture *rp;
 396        struct rcu_torture *rp1;
 397
 398        if (old_rp)
 399                list_add(&old_rp->rtort_free, &rcu_torture_removed);
 400        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 401                if (rcu_torture_pipe_update_one(rp)) {
 402                        list_del(&rp->rtort_free);
 403                        rcu_torture_free(rp);
 404                }
 405        }
 406}
 407
 408static void
 409rcu_torture_cb(struct rcu_head *p)
 410{
 411        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 412
 413        if (torture_must_stop_irq()) {
 414                /* Test is ending, just drop callbacks on the floor. */
 415                /* The next initialization will pick up the pieces. */
 416                return;
 417        }
 418        if (rcu_torture_pipe_update_one(rp))
 419                rcu_torture_free(rp);
 420        else
 421                cur_ops->deferred_free(rp);
 422}
 423
 424static unsigned long rcu_no_completed(void)
 425{
 426        return 0;
 427}
 428
 429static void rcu_torture_deferred_free(struct rcu_torture *p)
 430{
 431        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 432}
 433
 434static void rcu_sync_torture_init(void)
 435{
 436        INIT_LIST_HEAD(&rcu_torture_removed);
 437}
 438
 439static struct rcu_torture_ops rcu_ops = {
 440        .ttype          = RCU_FLAVOR,
 441        .init           = rcu_sync_torture_init,
 442        .readlock       = rcu_torture_read_lock,
 443        .read_delay     = rcu_read_delay,
 444        .readunlock     = rcu_torture_read_unlock,
 445        .get_gp_seq     = rcu_get_gp_seq,
 446        .gp_diff        = rcu_seq_diff,
 447        .deferred_free  = rcu_torture_deferred_free,
 448        .sync           = synchronize_rcu,
 449        .exp_sync       = synchronize_rcu_expedited,
 450        .get_state      = get_state_synchronize_rcu,
 451        .cond_sync      = cond_synchronize_rcu,
 452        .call           = call_rcu,
 453        .cb_barrier     = rcu_barrier,
 454        .fqs            = rcu_force_quiescent_state,
 455        .stats          = NULL,
 456        .stall_dur      = rcu_jiffies_till_stall_check,
 457        .irq_capable    = 1,
 458        .can_boost      = rcu_can_boost(),
 459        .extendables    = RCUTORTURE_MAX_EXTEND,
 460        .name           = "rcu"
 461};
 462
 463/*
 464 * Don't even think about trying any of these in real life!!!
 465 * The names includes "busted", and they really means it!
 466 * The only purpose of these functions is to provide a buggy RCU
 467 * implementation to make sure that rcutorture correctly emits
 468 * buggy-RCU error messages.
 469 */
 470static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 471{
 472        /* This is a deliberate bug for testing purposes only! */
 473        rcu_torture_cb(&p->rtort_rcu);
 474}
 475
 476static void synchronize_rcu_busted(void)
 477{
 478        /* This is a deliberate bug for testing purposes only! */
 479}
 480
 481static void
 482call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 483{
 484        /* This is a deliberate bug for testing purposes only! */
 485        func(head);
 486}
 487
 488static struct rcu_torture_ops rcu_busted_ops = {
 489        .ttype          = INVALID_RCU_FLAVOR,
 490        .init           = rcu_sync_torture_init,
 491        .readlock       = rcu_torture_read_lock,
 492        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 493        .readunlock     = rcu_torture_read_unlock,
 494        .get_gp_seq     = rcu_no_completed,
 495        .deferred_free  = rcu_busted_torture_deferred_free,
 496        .sync           = synchronize_rcu_busted,
 497        .exp_sync       = synchronize_rcu_busted,
 498        .call           = call_rcu_busted,
 499        .cb_barrier     = NULL,
 500        .fqs            = NULL,
 501        .stats          = NULL,
 502        .irq_capable    = 1,
 503        .name           = "busted"
 504};
 505
 506/*
 507 * Definitions for srcu torture testing.
 508 */
 509
 510DEFINE_STATIC_SRCU(srcu_ctl);
 511static struct srcu_struct srcu_ctld;
 512static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 513
 514static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 515{
 516        return srcu_read_lock(srcu_ctlp);
 517}
 518
 519static void
 520srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 521{
 522        long delay;
 523        const long uspertick = 1000000 / HZ;
 524        const long longdelay = 10;
 525
 526        /* We want there to be long-running readers, but not all the time. */
 527
 528        delay = torture_random(rrsp) %
 529                (nrealreaders * 2 * longdelay * uspertick);
 530        if (!delay && in_task()) {
 531                schedule_timeout_interruptible(longdelay);
 532                rtrsp->rt_delay_jiffies = longdelay;
 533        } else {
 534                rcu_read_delay(rrsp, rtrsp);
 535        }
 536}
 537
 538static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 539{
 540        srcu_read_unlock(srcu_ctlp, idx);
 541}
 542
 543static unsigned long srcu_torture_completed(void)
 544{
 545        return srcu_batches_completed(srcu_ctlp);
 546}
 547
 548static void srcu_torture_deferred_free(struct rcu_torture *rp)
 549{
 550        call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 551}
 552
 553static void srcu_torture_synchronize(void)
 554{
 555        synchronize_srcu(srcu_ctlp);
 556}
 557
 558static void srcu_torture_call(struct rcu_head *head,
 559                              rcu_callback_t func)
 560{
 561        call_srcu(srcu_ctlp, head, func);
 562}
 563
 564static void srcu_torture_barrier(void)
 565{
 566        srcu_barrier(srcu_ctlp);
 567}
 568
 569static void srcu_torture_stats(void)
 570{
 571        srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 572}
 573
 574static void srcu_torture_synchronize_expedited(void)
 575{
 576        synchronize_srcu_expedited(srcu_ctlp);
 577}
 578
 579static struct rcu_torture_ops srcu_ops = {
 580        .ttype          = SRCU_FLAVOR,
 581        .init           = rcu_sync_torture_init,
 582        .readlock       = srcu_torture_read_lock,
 583        .read_delay     = srcu_read_delay,
 584        .readunlock     = srcu_torture_read_unlock,
 585        .get_gp_seq     = srcu_torture_completed,
 586        .deferred_free  = srcu_torture_deferred_free,
 587        .sync           = srcu_torture_synchronize,
 588        .exp_sync       = srcu_torture_synchronize_expedited,
 589        .call           = srcu_torture_call,
 590        .cb_barrier     = srcu_torture_barrier,
 591        .stats          = srcu_torture_stats,
 592        .irq_capable    = 1,
 593        .name           = "srcu"
 594};
 595
 596static void srcu_torture_init(void)
 597{
 598        rcu_sync_torture_init();
 599        WARN_ON(init_srcu_struct(&srcu_ctld));
 600        srcu_ctlp = &srcu_ctld;
 601}
 602
 603static void srcu_torture_cleanup(void)
 604{
 605        cleanup_srcu_struct(&srcu_ctld);
 606        srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 607}
 608
 609/* As above, but dynamically allocated. */
 610static struct rcu_torture_ops srcud_ops = {
 611        .ttype          = SRCU_FLAVOR,
 612        .init           = srcu_torture_init,
 613        .cleanup        = srcu_torture_cleanup,
 614        .readlock       = srcu_torture_read_lock,
 615        .read_delay     = srcu_read_delay,
 616        .readunlock     = srcu_torture_read_unlock,
 617        .get_gp_seq     = srcu_torture_completed,
 618        .deferred_free  = srcu_torture_deferred_free,
 619        .sync           = srcu_torture_synchronize,
 620        .exp_sync       = srcu_torture_synchronize_expedited,
 621        .call           = srcu_torture_call,
 622        .cb_barrier     = srcu_torture_barrier,
 623        .stats          = srcu_torture_stats,
 624        .irq_capable    = 1,
 625        .name           = "srcud"
 626};
 627
 628/* As above, but broken due to inappropriate reader extension. */
 629static struct rcu_torture_ops busted_srcud_ops = {
 630        .ttype          = SRCU_FLAVOR,
 631        .init           = srcu_torture_init,
 632        .cleanup        = srcu_torture_cleanup,
 633        .readlock       = srcu_torture_read_lock,
 634        .read_delay     = rcu_read_delay,
 635        .readunlock     = srcu_torture_read_unlock,
 636        .get_gp_seq     = srcu_torture_completed,
 637        .deferred_free  = srcu_torture_deferred_free,
 638        .sync           = srcu_torture_synchronize,
 639        .exp_sync       = srcu_torture_synchronize_expedited,
 640        .call           = srcu_torture_call,
 641        .cb_barrier     = srcu_torture_barrier,
 642        .stats          = srcu_torture_stats,
 643        .irq_capable    = 1,
 644        .extendables    = RCUTORTURE_MAX_EXTEND,
 645        .name           = "busted_srcud"
 646};
 647
 648/*
 649 * Definitions for RCU-tasks torture testing.
 650 */
 651
 652static int tasks_torture_read_lock(void)
 653{
 654        return 0;
 655}
 656
 657static void tasks_torture_read_unlock(int idx)
 658{
 659}
 660
 661static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 662{
 663        call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 664}
 665
 666static struct rcu_torture_ops tasks_ops = {
 667        .ttype          = RCU_TASKS_FLAVOR,
 668        .init           = rcu_sync_torture_init,
 669        .readlock       = tasks_torture_read_lock,
 670        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 671        .readunlock     = tasks_torture_read_unlock,
 672        .get_gp_seq     = rcu_no_completed,
 673        .deferred_free  = rcu_tasks_torture_deferred_free,
 674        .sync           = synchronize_rcu_tasks,
 675        .exp_sync       = synchronize_rcu_tasks,
 676        .call           = call_rcu_tasks,
 677        .cb_barrier     = rcu_barrier_tasks,
 678        .fqs            = NULL,
 679        .stats          = NULL,
 680        .irq_capable    = 1,
 681        .slow_gps       = 1,
 682        .name           = "tasks"
 683};
 684
 685/*
 686 * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 687 * This implementation does not necessarily work well with CPU hotplug.
 688 */
 689
 690static void synchronize_rcu_trivial(void)
 691{
 692        int cpu;
 693
 694        for_each_online_cpu(cpu) {
 695                rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 696                WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 697        }
 698}
 699
 700static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 701{
 702        preempt_disable();
 703        return 0;
 704}
 705
 706static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 707{
 708        preempt_enable();
 709}
 710
 711static struct rcu_torture_ops trivial_ops = {
 712        .ttype          = RCU_TRIVIAL_FLAVOR,
 713        .init           = rcu_sync_torture_init,
 714        .readlock       = rcu_torture_read_lock_trivial,
 715        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 716        .readunlock     = rcu_torture_read_unlock_trivial,
 717        .get_gp_seq     = rcu_no_completed,
 718        .sync           = synchronize_rcu_trivial,
 719        .exp_sync       = synchronize_rcu_trivial,
 720        .fqs            = NULL,
 721        .stats          = NULL,
 722        .irq_capable    = 1,
 723        .name           = "trivial"
 724};
 725
 726static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 727{
 728        if (!cur_ops->gp_diff)
 729                return new - old;
 730        return cur_ops->gp_diff(new, old);
 731}
 732
 733static bool __maybe_unused torturing_tasks(void)
 734{
 735        return cur_ops == &tasks_ops;
 736}
 737
 738/*
 739 * RCU torture priority-boost testing.  Runs one real-time thread per
 740 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 741 * spinning waiting for them to be invoked.  If a given callback takes
 742 * too long to be invoked, we assume that priority inversion has occurred.
 743 */
 744
 745struct rcu_boost_inflight {
 746        struct rcu_head rcu;
 747        int inflight;
 748};
 749
 750static void rcu_torture_boost_cb(struct rcu_head *head)
 751{
 752        struct rcu_boost_inflight *rbip =
 753                container_of(head, struct rcu_boost_inflight, rcu);
 754
 755        /* Ensure RCU-core accesses precede clearing ->inflight */
 756        smp_store_release(&rbip->inflight, 0);
 757}
 758
 759static int old_rt_runtime = -1;
 760
 761static void rcu_torture_disable_rt_throttle(void)
 762{
 763        /*
 764         * Disable RT throttling so that rcutorture's boost threads don't get
 765         * throttled. Only possible if rcutorture is built-in otherwise the
 766         * user should manually do this by setting the sched_rt_period_us and
 767         * sched_rt_runtime sysctls.
 768         */
 769        if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 770                return;
 771
 772        old_rt_runtime = sysctl_sched_rt_runtime;
 773        sysctl_sched_rt_runtime = -1;
 774}
 775
 776static void rcu_torture_enable_rt_throttle(void)
 777{
 778        if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 779                return;
 780
 781        sysctl_sched_rt_runtime = old_rt_runtime;
 782        old_rt_runtime = -1;
 783}
 784
 785static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 786{
 787        if (end - start > test_boost_duration * HZ - HZ / 2) {
 788                VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 789                n_rcu_torture_boost_failure++;
 790
 791                return true; /* failed */
 792        }
 793
 794        return false; /* passed */
 795}
 796
 797static int rcu_torture_boost(void *arg)
 798{
 799        unsigned long call_rcu_time;
 800        unsigned long endtime;
 801        unsigned long oldstarttime;
 802        struct rcu_boost_inflight rbi = { .inflight = 0 };
 803        struct sched_param sp;
 804
 805        VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 806
 807        /* Set real-time priority. */
 808        sp.sched_priority = 1;
 809        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 810                VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 811                n_rcu_torture_boost_rterror++;
 812        }
 813
 814        init_rcu_head_on_stack(&rbi.rcu);
 815        /* Each pass through the following loop does one boost-test cycle. */
 816        do {
 817                /* Track if the test failed already in this test interval? */
 818                bool failed = false;
 819
 820                /* Increment n_rcu_torture_boosts once per boost-test */
 821                while (!kthread_should_stop()) {
 822                        if (mutex_trylock(&boost_mutex)) {
 823                                n_rcu_torture_boosts++;
 824                                mutex_unlock(&boost_mutex);
 825                                break;
 826                        }
 827                        schedule_timeout_uninterruptible(1);
 828                }
 829                if (kthread_should_stop())
 830                        goto checkwait;
 831
 832                /* Wait for the next test interval. */
 833                oldstarttime = boost_starttime;
 834                while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 835                        schedule_timeout_interruptible(oldstarttime - jiffies);
 836                        stutter_wait("rcu_torture_boost");
 837                        if (torture_must_stop())
 838                                goto checkwait;
 839                }
 840
 841                /* Do one boost-test interval. */
 842                endtime = oldstarttime + test_boost_duration * HZ;
 843                call_rcu_time = jiffies;
 844                while (ULONG_CMP_LT(jiffies, endtime)) {
 845                        /* If we don't have a callback in flight, post one. */
 846                        if (!smp_load_acquire(&rbi.inflight)) {
 847                                /* RCU core before ->inflight = 1. */
 848                                smp_store_release(&rbi.inflight, 1);
 849                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 850                                /* Check if the boost test failed */
 851                                failed = failed ||
 852                                         rcu_torture_boost_failed(call_rcu_time,
 853                                                                 jiffies);
 854                                call_rcu_time = jiffies;
 855                        }
 856                        stutter_wait("rcu_torture_boost");
 857                        if (torture_must_stop())
 858                                goto checkwait;
 859                }
 860
 861                /*
 862                 * If boost never happened, then inflight will always be 1, in
 863                 * this case the boost check would never happen in the above
 864                 * loop so do another one here.
 865                 */
 866                if (!failed && smp_load_acquire(&rbi.inflight))
 867                        rcu_torture_boost_failed(call_rcu_time, jiffies);
 868
 869                /*
 870                 * Set the start time of the next test interval.
 871                 * Yes, this is vulnerable to long delays, but such
 872                 * delays simply cause a false negative for the next
 873                 * interval.  Besides, we are running at RT priority,
 874                 * so delays should be relatively rare.
 875                 */
 876                while (oldstarttime == boost_starttime &&
 877                       !kthread_should_stop()) {
 878                        if (mutex_trylock(&boost_mutex)) {
 879                                boost_starttime = jiffies +
 880                                                  test_boost_interval * HZ;
 881                                mutex_unlock(&boost_mutex);
 882                                break;
 883                        }
 884                        schedule_timeout_uninterruptible(1);
 885                }
 886
 887                /* Go do the stutter. */
 888checkwait:      stutter_wait("rcu_torture_boost");
 889        } while (!torture_must_stop());
 890
 891        /* Clean up and exit. */
 892        while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 893                torture_shutdown_absorb("rcu_torture_boost");
 894                schedule_timeout_uninterruptible(1);
 895        }
 896        destroy_rcu_head_on_stack(&rbi.rcu);
 897        torture_kthread_stopping("rcu_torture_boost");
 898        return 0;
 899}
 900
 901/*
 902 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 903 * bursts of calls to force_quiescent_state(), increasing the probability
 904 * of occurrence of some important types of race conditions.
 905 */
 906static int
 907rcu_torture_fqs(void *arg)
 908{
 909        unsigned long fqs_resume_time;
 910        int fqs_burst_remaining;
 911
 912        VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 913        do {
 914                fqs_resume_time = jiffies + fqs_stutter * HZ;
 915                while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 916                       !kthread_should_stop()) {
 917                        schedule_timeout_interruptible(1);
 918                }
 919                fqs_burst_remaining = fqs_duration;
 920                while (fqs_burst_remaining > 0 &&
 921                       !kthread_should_stop()) {
 922                        cur_ops->fqs();
 923                        udelay(fqs_holdoff);
 924                        fqs_burst_remaining -= fqs_holdoff;
 925                }
 926                stutter_wait("rcu_torture_fqs");
 927        } while (!torture_must_stop());
 928        torture_kthread_stopping("rcu_torture_fqs");
 929        return 0;
 930}
 931
 932/*
 933 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 934 * for that pointed to by rcu_torture_current, freeing the old structure
 935 * after a series of grace periods (the "pipeline").
 936 */
 937static int
 938rcu_torture_writer(void *arg)
 939{
 940        bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 941        int expediting = 0;
 942        unsigned long gp_snap;
 943        bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 944        bool gp_sync1 = gp_sync;
 945        int i;
 946        struct rcu_torture *rp;
 947        struct rcu_torture *old_rp;
 948        static DEFINE_TORTURE_RANDOM(rand);
 949        int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 950                           RTWS_COND_GET, RTWS_SYNC };
 951        int nsynctypes = 0;
 952
 953        VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 954        if (!can_expedite)
 955                pr_alert("%s" TORTURE_FLAG
 956                         " GP expediting controlled from boot/sysfs for %s.\n",
 957                         torture_type, cur_ops->name);
 958
 959        /* Initialize synctype[] array.  If none set, take default. */
 960        if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 961                gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 962        if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 963                synctype[nsynctypes++] = RTWS_COND_GET;
 964                pr_info("%s: Testing conditional GPs.\n", __func__);
 965        } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 966                pr_alert("%s: gp_cond without primitives.\n", __func__);
 967        }
 968        if (gp_exp1 && cur_ops->exp_sync) {
 969                synctype[nsynctypes++] = RTWS_EXP_SYNC;
 970                pr_info("%s: Testing expedited GPs.\n", __func__);
 971        } else if (gp_exp && !cur_ops->exp_sync) {
 972                pr_alert("%s: gp_exp without primitives.\n", __func__);
 973        }
 974        if (gp_normal1 && cur_ops->deferred_free) {
 975                synctype[nsynctypes++] = RTWS_DEF_FREE;
 976                pr_info("%s: Testing asynchronous GPs.\n", __func__);
 977        } else if (gp_normal && !cur_ops->deferred_free) {
 978                pr_alert("%s: gp_normal without primitives.\n", __func__);
 979        }
 980        if (gp_sync1 && cur_ops->sync) {
 981                synctype[nsynctypes++] = RTWS_SYNC;
 982                pr_info("%s: Testing normal GPs.\n", __func__);
 983        } else if (gp_sync && !cur_ops->sync) {
 984                pr_alert("%s: gp_sync without primitives.\n", __func__);
 985        }
 986        if (WARN_ONCE(nsynctypes == 0,
 987                      "rcu_torture_writer: No update-side primitives.\n")) {
 988                /*
 989                 * No updates primitives, so don't try updating.
 990                 * The resulting test won't be testing much, hence the
 991                 * above WARN_ONCE().
 992                 */
 993                rcu_torture_writer_state = RTWS_STOPPING;
 994                torture_kthread_stopping("rcu_torture_writer");
 995        }
 996
 997        do {
 998                rcu_torture_writer_state = RTWS_FIXED_DELAY;
 999                schedule_timeout_uninterruptible(1);
1000                rp = rcu_torture_alloc();
1001                if (rp == NULL)
1002                        continue;
1003                rp->rtort_pipe_count = 0;
1004                rcu_torture_writer_state = RTWS_DELAY;
1005                udelay(torture_random(&rand) & 0x3ff);
1006                rcu_torture_writer_state = RTWS_REPLACE;
1007                old_rp = rcu_dereference_check(rcu_torture_current,
1008                                               current == writer_task);
1009                rp->rtort_mbtest = 1;
1010                rcu_assign_pointer(rcu_torture_current, rp);
1011                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1012                if (old_rp) {
1013                        i = old_rp->rtort_pipe_count;
1014                        if (i > RCU_TORTURE_PIPE_LEN)
1015                                i = RCU_TORTURE_PIPE_LEN;
1016                        atomic_inc(&rcu_torture_wcount[i]);
1017                        old_rp->rtort_pipe_count++;
1018                        switch (synctype[torture_random(&rand) % nsynctypes]) {
1019                        case RTWS_DEF_FREE:
1020                                rcu_torture_writer_state = RTWS_DEF_FREE;
1021                                cur_ops->deferred_free(old_rp);
1022                                break;
1023                        case RTWS_EXP_SYNC:
1024                                rcu_torture_writer_state = RTWS_EXP_SYNC;
1025                                cur_ops->exp_sync();
1026                                rcu_torture_pipe_update(old_rp);
1027                                break;
1028                        case RTWS_COND_GET:
1029                                rcu_torture_writer_state = RTWS_COND_GET;
1030                                gp_snap = cur_ops->get_state();
1031                                i = torture_random(&rand) % 16;
1032                                if (i != 0)
1033                                        schedule_timeout_interruptible(i);
1034                                udelay(torture_random(&rand) % 1000);
1035                                rcu_torture_writer_state = RTWS_COND_SYNC;
1036                                cur_ops->cond_sync(gp_snap);
1037                                rcu_torture_pipe_update(old_rp);
1038                                break;
1039                        case RTWS_SYNC:
1040                                rcu_torture_writer_state = RTWS_SYNC;
1041                                cur_ops->sync();
1042                                rcu_torture_pipe_update(old_rp);
1043                                break;
1044                        default:
1045                                WARN_ON_ONCE(1);
1046                                break;
1047                        }
1048                }
1049                WRITE_ONCE(rcu_torture_current_version,
1050                           rcu_torture_current_version + 1);
1051                /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1052                if (can_expedite &&
1053                    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1054                        WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1055                        if (expediting >= 0)
1056                                rcu_expedite_gp();
1057                        else
1058                                rcu_unexpedite_gp();
1059                        if (++expediting > 3)
1060                                expediting = -expediting;
1061                } else if (!can_expedite) { /* Disabled during boot, recheck. */
1062                        can_expedite = !rcu_gp_is_expedited() &&
1063                                       !rcu_gp_is_normal();
1064                }
1065                rcu_torture_writer_state = RTWS_STUTTER;
1066                if (stutter_wait("rcu_torture_writer") &&
1067                    !READ_ONCE(rcu_fwd_cb_nodelay) &&
1068                    !cur_ops->slow_gps &&
1069                    !torture_must_stop())
1070                        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1071                                if (list_empty(&rcu_tortures[i].rtort_free) &&
1072                                    rcu_access_pointer(rcu_torture_current) !=
1073                                    &rcu_tortures[i]) {
1074                                        rcu_ftrace_dump(DUMP_ALL);
1075                                        WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1076                                }
1077        } while (!torture_must_stop());
1078        /* Reset expediting back to unexpedited. */
1079        if (expediting > 0)
1080                expediting = -expediting;
1081        while (can_expedite && expediting++ < 0)
1082                rcu_unexpedite_gp();
1083        WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1084        if (!can_expedite)
1085                pr_alert("%s" TORTURE_FLAG
1086                         " Dynamic grace-period expediting was disabled.\n",
1087                         torture_type);
1088        rcu_torture_writer_state = RTWS_STOPPING;
1089        torture_kthread_stopping("rcu_torture_writer");
1090        return 0;
1091}
1092
1093/*
1094 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1095 * delay between calls.
1096 */
1097static int
1098rcu_torture_fakewriter(void *arg)
1099{
1100        DEFINE_TORTURE_RANDOM(rand);
1101
1102        VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1103        set_user_nice(current, MAX_NICE);
1104
1105        do {
1106                schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1107                udelay(torture_random(&rand) & 0x3ff);
1108                if (cur_ops->cb_barrier != NULL &&
1109                    torture_random(&rand) % (nfakewriters * 8) == 0) {
1110                        cur_ops->cb_barrier();
1111                } else if (gp_normal == gp_exp) {
1112                        if (cur_ops->sync && torture_random(&rand) & 0x80)
1113                                cur_ops->sync();
1114                        else if (cur_ops->exp_sync)
1115                                cur_ops->exp_sync();
1116                } else if (gp_normal && cur_ops->sync) {
1117                        cur_ops->sync();
1118                } else if (cur_ops->exp_sync) {
1119                        cur_ops->exp_sync();
1120                }
1121                stutter_wait("rcu_torture_fakewriter");
1122        } while (!torture_must_stop());
1123
1124        torture_kthread_stopping("rcu_torture_fakewriter");
1125        return 0;
1126}
1127
1128static void rcu_torture_timer_cb(struct rcu_head *rhp)
1129{
1130        kfree(rhp);
1131}
1132
1133/*
1134 * Do one extension of an RCU read-side critical section using the
1135 * current reader state in readstate (set to zero for initial entry
1136 * to extended critical section), set the new state as specified by
1137 * newstate (set to zero for final exit from extended critical section),
1138 * and random-number-generator state in trsp.  If this is neither the
1139 * beginning or end of the critical section and if there was actually a
1140 * change, do a ->read_delay().
1141 */
1142static void rcutorture_one_extend(int *readstate, int newstate,
1143                                  struct torture_random_state *trsp,
1144                                  struct rt_read_seg *rtrsp)
1145{
1146        int idxnew = -1;
1147        int idxold = *readstate;
1148        int statesnew = ~*readstate & newstate;
1149        int statesold = *readstate & ~newstate;
1150
1151        WARN_ON_ONCE(idxold < 0);
1152        WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1153        rtrsp->rt_readstate = newstate;
1154
1155        /* First, put new protection in place to avoid critical-section gap. */
1156        if (statesnew & RCUTORTURE_RDR_BH)
1157                local_bh_disable();
1158        if (statesnew & RCUTORTURE_RDR_IRQ)
1159                local_irq_disable();
1160        if (statesnew & RCUTORTURE_RDR_PREEMPT)
1161                preempt_disable();
1162        if (statesnew & RCUTORTURE_RDR_RBH)
1163                rcu_read_lock_bh();
1164        if (statesnew & RCUTORTURE_RDR_SCHED)
1165                rcu_read_lock_sched();
1166        if (statesnew & RCUTORTURE_RDR_RCU)
1167                idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1168
1169        /* Next, remove old protection, irq first due to bh conflict. */
1170        if (statesold & RCUTORTURE_RDR_IRQ)
1171                local_irq_enable();
1172        if (statesold & RCUTORTURE_RDR_BH)
1173                local_bh_enable();
1174        if (statesold & RCUTORTURE_RDR_PREEMPT)
1175                preempt_enable();
1176        if (statesold & RCUTORTURE_RDR_RBH)
1177                rcu_read_unlock_bh();
1178        if (statesold & RCUTORTURE_RDR_SCHED)
1179                rcu_read_unlock_sched();
1180        if (statesold & RCUTORTURE_RDR_RCU)
1181                cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1182
1183        /* Delay if neither beginning nor end and there was a change. */
1184        if ((statesnew || statesold) && *readstate && newstate)
1185                cur_ops->read_delay(trsp, rtrsp);
1186
1187        /* Update the reader state. */
1188        if (idxnew == -1)
1189                idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1190        WARN_ON_ONCE(idxnew < 0);
1191        WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1192        *readstate = idxnew | newstate;
1193        WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1194        WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1195}
1196
1197/* Return the biggest extendables mask given current RCU and boot parameters. */
1198static int rcutorture_extend_mask_max(void)
1199{
1200        int mask;
1201
1202        WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1203        mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1204        mask = mask | RCUTORTURE_RDR_RCU;
1205        return mask;
1206}
1207
1208/* Return a random protection state mask, but with at least one bit set. */
1209static int
1210rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1211{
1212        int mask = rcutorture_extend_mask_max();
1213        unsigned long randmask1 = torture_random(trsp) >> 8;
1214        unsigned long randmask2 = randmask1 >> 3;
1215
1216        WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1217        /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1218        if (!(randmask1 & 0x7))
1219                mask = mask & randmask2;
1220        else
1221                mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1222        /* Can't enable bh w/irq disabled. */
1223        if ((mask & RCUTORTURE_RDR_IRQ) &&
1224            ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1225             (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1226                mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1227        return mask ?: RCUTORTURE_RDR_RCU;
1228}
1229
1230/*
1231 * Do a randomly selected number of extensions of an existing RCU read-side
1232 * critical section.
1233 */
1234static struct rt_read_seg *
1235rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1236                       struct rt_read_seg *rtrsp)
1237{
1238        int i;
1239        int j;
1240        int mask = rcutorture_extend_mask_max();
1241
1242        WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1243        if (!((mask - 1) & mask))
1244                return rtrsp;  /* Current RCU reader not extendable. */
1245        /* Bias towards larger numbers of loops. */
1246        i = (torture_random(trsp) >> 3);
1247        i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1248        for (j = 0; j < i; j++) {
1249                mask = rcutorture_extend_mask(*readstate, trsp);
1250                rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1251        }
1252        return &rtrsp[j];
1253}
1254
1255/*
1256 * Do one read-side critical section, returning false if there was
1257 * no data to read.  Can be invoked both from process context and
1258 * from a timer handler.
1259 */
1260static bool rcu_torture_one_read(struct torture_random_state *trsp)
1261{
1262        int i;
1263        unsigned long started;
1264        unsigned long completed;
1265        int newstate;
1266        struct rcu_torture *p;
1267        int pipe_count;
1268        int readstate = 0;
1269        struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1270        struct rt_read_seg *rtrsp = &rtseg[0];
1271        struct rt_read_seg *rtrsp1;
1272        unsigned long long ts;
1273
1274        newstate = rcutorture_extend_mask(readstate, trsp);
1275        rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1276        started = cur_ops->get_gp_seq();
1277        ts = rcu_trace_clock_local();
1278        p = rcu_dereference_check(rcu_torture_current,
1279                                  rcu_read_lock_bh_held() ||
1280                                  rcu_read_lock_sched_held() ||
1281                                  srcu_read_lock_held(srcu_ctlp) ||
1282                                  torturing_tasks());
1283        if (p == NULL) {
1284                /* Wait for rcu_torture_writer to get underway */
1285                rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1286                return false;
1287        }
1288        if (p->rtort_mbtest == 0)
1289                atomic_inc(&n_rcu_torture_mberror);
1290        rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1291        preempt_disable();
1292        pipe_count = p->rtort_pipe_count;
1293        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1294                /* Should not happen, but... */
1295                pipe_count = RCU_TORTURE_PIPE_LEN;
1296        }
1297        completed = cur_ops->get_gp_seq();
1298        if (pipe_count > 1) {
1299                do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1300                                          ts, started, completed);
1301                rcu_ftrace_dump(DUMP_ALL);
1302        }
1303        __this_cpu_inc(rcu_torture_count[pipe_count]);
1304        completed = rcutorture_seq_diff(completed, started);
1305        if (completed > RCU_TORTURE_PIPE_LEN) {
1306                /* Should not happen, but... */
1307                completed = RCU_TORTURE_PIPE_LEN;
1308        }
1309        __this_cpu_inc(rcu_torture_batch[completed]);
1310        preempt_enable();
1311        rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1312        WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1313
1314        /* If error or close call, record the sequence of reader protections. */
1315        if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1316                i = 0;
1317                for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1318                        err_segs[i++] = *rtrsp1;
1319                rt_read_nsegs = i;
1320        }
1321
1322        return true;
1323}
1324
1325static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1326
1327/*
1328 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1329 * incrementing the corresponding element of the pipeline array.  The
1330 * counter in the element should never be greater than 1, otherwise, the
1331 * RCU implementation is broken.
1332 */
1333static void rcu_torture_timer(struct timer_list *unused)
1334{
1335        atomic_long_inc(&n_rcu_torture_timers);
1336        (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1337
1338        /* Test call_rcu() invocation from interrupt handler. */
1339        if (cur_ops->call) {
1340                struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1341
1342                if (rhp)
1343                        cur_ops->call(rhp, rcu_torture_timer_cb);
1344        }
1345}
1346
1347/*
1348 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1349 * incrementing the corresponding element of the pipeline array.  The
1350 * counter in the element should never be greater than 1, otherwise, the
1351 * RCU implementation is broken.
1352 */
1353static int
1354rcu_torture_reader(void *arg)
1355{
1356        unsigned long lastsleep = jiffies;
1357        long myid = (long)arg;
1358        int mynumonline = myid;
1359        DEFINE_TORTURE_RANDOM(rand);
1360        struct timer_list t;
1361
1362        VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1363        set_user_nice(current, MAX_NICE);
1364        if (irqreader && cur_ops->irq_capable)
1365                timer_setup_on_stack(&t, rcu_torture_timer, 0);
1366
1367        do {
1368                if (irqreader && cur_ops->irq_capable) {
1369                        if (!timer_pending(&t))
1370                                mod_timer(&t, jiffies + 1);
1371                }
1372                if (!rcu_torture_one_read(&rand))
1373                        schedule_timeout_interruptible(HZ);
1374                if (time_after(jiffies, lastsleep)) {
1375                        schedule_timeout_interruptible(1);
1376                        lastsleep = jiffies + 10;
1377                }
1378                while (num_online_cpus() < mynumonline && !torture_must_stop())
1379                        schedule_timeout_interruptible(HZ / 5);
1380                stutter_wait("rcu_torture_reader");
1381        } while (!torture_must_stop());
1382        if (irqreader && cur_ops->irq_capable) {
1383                del_timer_sync(&t);
1384                destroy_timer_on_stack(&t);
1385        }
1386        torture_kthread_stopping("rcu_torture_reader");
1387        return 0;
1388}
1389
1390/*
1391 * Print torture statistics.  Caller must ensure that there is only
1392 * one call to this function at a given time!!!  This is normally
1393 * accomplished by relying on the module system to only have one copy
1394 * of the module loaded, and then by giving the rcu_torture_stats
1395 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1396 * thread is not running).
1397 */
1398static void
1399rcu_torture_stats_print(void)
1400{
1401        int cpu;
1402        int i;
1403        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1404        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1405        static unsigned long rtcv_snap = ULONG_MAX;
1406        static bool splatted;
1407        struct task_struct *wtp;
1408
1409        for_each_possible_cpu(cpu) {
1410                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1411                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1412                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1413                }
1414        }
1415        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1416                if (pipesummary[i] != 0)
1417                        break;
1418        }
1419
1420        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1421        pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1422                rcu_torture_current,
1423                rcu_torture_current ? "ver" : "VER",
1424                rcu_torture_current_version,
1425                list_empty(&rcu_torture_freelist),
1426                atomic_read(&n_rcu_torture_alloc),
1427                atomic_read(&n_rcu_torture_alloc_fail),
1428                atomic_read(&n_rcu_torture_free));
1429        pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1430                atomic_read(&n_rcu_torture_mberror),
1431                n_rcu_torture_barrier_error,
1432                n_rcu_torture_boost_ktrerror,
1433                n_rcu_torture_boost_rterror);
1434        pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1435                n_rcu_torture_boost_failure,
1436                n_rcu_torture_boosts,
1437                atomic_long_read(&n_rcu_torture_timers));
1438        torture_onoff_stats();
1439        pr_cont("barrier: %ld/%ld:%ld\n",
1440                n_barrier_successes,
1441                n_barrier_attempts,
1442                n_rcu_torture_barrier_error);
1443
1444        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1445        if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1446            n_rcu_torture_barrier_error != 0 ||
1447            n_rcu_torture_boost_ktrerror != 0 ||
1448            n_rcu_torture_boost_rterror != 0 ||
1449            n_rcu_torture_boost_failure != 0 ||
1450            i > 1) {
1451                pr_cont("%s", "!!! ");
1452                atomic_inc(&n_rcu_torture_error);
1453                WARN_ON_ONCE(1);
1454        }
1455        pr_cont("Reader Pipe: ");
1456        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1457                pr_cont(" %ld", pipesummary[i]);
1458        pr_cont("\n");
1459
1460        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1461        pr_cont("Reader Batch: ");
1462        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1463                pr_cont(" %ld", batchsummary[i]);
1464        pr_cont("\n");
1465
1466        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1467        pr_cont("Free-Block Circulation: ");
1468        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1469                pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1470        }
1471        pr_cont("\n");
1472
1473        if (cur_ops->stats)
1474                cur_ops->stats();
1475        if (rtcv_snap == rcu_torture_current_version &&
1476            rcu_torture_current != NULL) {
1477                int __maybe_unused flags = 0;
1478                unsigned long __maybe_unused gp_seq = 0;
1479
1480                rcutorture_get_gp_data(cur_ops->ttype,
1481                                       &flags, &gp_seq);
1482                srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1483                                        &flags, &gp_seq);
1484                wtp = READ_ONCE(writer_task);
1485                pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1486                         rcu_torture_writer_state_getname(),
1487                         rcu_torture_writer_state, gp_seq, flags,
1488                         wtp == NULL ? ~0UL : wtp->state,
1489                         wtp == NULL ? -1 : (int)task_cpu(wtp));
1490                if (!splatted && wtp) {
1491                        sched_show_task(wtp);
1492                        splatted = true;
1493                }
1494                show_rcu_gp_kthreads();
1495                rcu_ftrace_dump(DUMP_ALL);
1496        }
1497        rtcv_snap = rcu_torture_current_version;
1498}
1499
1500/*
1501 * Periodically prints torture statistics, if periodic statistics printing
1502 * was specified via the stat_interval module parameter.
1503 */
1504static int
1505rcu_torture_stats(void *arg)
1506{
1507        VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1508        do {
1509                schedule_timeout_interruptible(stat_interval * HZ);
1510                rcu_torture_stats_print();
1511                torture_shutdown_absorb("rcu_torture_stats");
1512        } while (!torture_must_stop());
1513        torture_kthread_stopping("rcu_torture_stats");
1514        return 0;
1515}
1516
1517static void
1518rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1519{
1520        pr_alert("%s" TORTURE_FLAG
1521                 "--- %s: nreaders=%d nfakewriters=%d "
1522                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1523                 "shuffle_interval=%d stutter=%d irqreader=%d "
1524                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1525                 "test_boost=%d/%d test_boost_interval=%d "
1526                 "test_boost_duration=%d shutdown_secs=%d "
1527                 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1528                 "n_barrier_cbs=%d "
1529                 "onoff_interval=%d onoff_holdoff=%d\n",
1530                 torture_type, tag, nrealreaders, nfakewriters,
1531                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1532                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1533                 test_boost, cur_ops->can_boost,
1534                 test_boost_interval, test_boost_duration, shutdown_secs,
1535                 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1536                 n_barrier_cbs,
1537                 onoff_interval, onoff_holdoff);
1538}
1539
1540static int rcutorture_booster_cleanup(unsigned int cpu)
1541{
1542        struct task_struct *t;
1543
1544        if (boost_tasks[cpu] == NULL)
1545                return 0;
1546        mutex_lock(&boost_mutex);
1547        t = boost_tasks[cpu];
1548        boost_tasks[cpu] = NULL;
1549        rcu_torture_enable_rt_throttle();
1550        mutex_unlock(&boost_mutex);
1551
1552        /* This must be outside of the mutex, otherwise deadlock! */
1553        torture_stop_kthread(rcu_torture_boost, t);
1554        return 0;
1555}
1556
1557static int rcutorture_booster_init(unsigned int cpu)
1558{
1559        int retval;
1560
1561        if (boost_tasks[cpu] != NULL)
1562                return 0;  /* Already created, nothing more to do. */
1563
1564        /* Don't allow time recalculation while creating a new task. */
1565        mutex_lock(&boost_mutex);
1566        rcu_torture_disable_rt_throttle();
1567        VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1568        boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1569                                                  cpu_to_node(cpu),
1570                                                  "rcu_torture_boost");
1571        if (IS_ERR(boost_tasks[cpu])) {
1572                retval = PTR_ERR(boost_tasks[cpu]);
1573                VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1574                n_rcu_torture_boost_ktrerror++;
1575                boost_tasks[cpu] = NULL;
1576                mutex_unlock(&boost_mutex);
1577                return retval;
1578        }
1579        kthread_bind(boost_tasks[cpu], cpu);
1580        wake_up_process(boost_tasks[cpu]);
1581        mutex_unlock(&boost_mutex);
1582        return 0;
1583}
1584
1585/*
1586 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1587 * induces a CPU stall for the time specified by stall_cpu.
1588 */
1589static int rcu_torture_stall(void *args)
1590{
1591        unsigned long stop_at;
1592
1593        VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1594        if (stall_cpu_holdoff > 0) {
1595                VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1596                schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1597                VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1598        }
1599        if (!kthread_should_stop()) {
1600                stop_at = ktime_get_seconds() + stall_cpu;
1601                /* RCU CPU stall is expected behavior in following code. */
1602                rcu_read_lock();
1603                if (stall_cpu_irqsoff)
1604                        local_irq_disable();
1605                else
1606                        preempt_disable();
1607                pr_alert("rcu_torture_stall start on CPU %d.\n",
1608                         smp_processor_id());
1609                while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1610                                    stop_at))
1611                        continue;  /* Induce RCU CPU stall warning. */
1612                if (stall_cpu_irqsoff)
1613                        local_irq_enable();
1614                else
1615                        preempt_enable();
1616                rcu_read_unlock();
1617                pr_alert("rcu_torture_stall end.\n");
1618        }
1619        torture_shutdown_absorb("rcu_torture_stall");
1620        while (!kthread_should_stop())
1621                schedule_timeout_interruptible(10 * HZ);
1622        return 0;
1623}
1624
1625/* Spawn CPU-stall kthread, if stall_cpu specified. */
1626static int __init rcu_torture_stall_init(void)
1627{
1628        if (stall_cpu <= 0)
1629                return 0;
1630        return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1631}
1632
1633/* State structure for forward-progress self-propagating RCU callback. */
1634struct fwd_cb_state {
1635        struct rcu_head rh;
1636        int stop;
1637};
1638
1639/*
1640 * Forward-progress self-propagating RCU callback function.  Because
1641 * callbacks run from softirq, this function is an implicit RCU read-side
1642 * critical section.
1643 */
1644static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1645{
1646        struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1647
1648        if (READ_ONCE(fcsp->stop)) {
1649                WRITE_ONCE(fcsp->stop, 2);
1650                return;
1651        }
1652        cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1653}
1654
1655/* State for continuous-flood RCU callbacks. */
1656struct rcu_fwd_cb {
1657        struct rcu_head rh;
1658        struct rcu_fwd_cb *rfc_next;
1659        int rfc_gps;
1660};
1661static DEFINE_SPINLOCK(rcu_fwd_lock);
1662static struct rcu_fwd_cb *rcu_fwd_cb_head;
1663static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1664static long n_launders_cb;
1665static unsigned long rcu_fwd_startat;
1666static bool rcu_fwd_emergency_stop;
1667#define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1668#define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1669#define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1670#define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1671struct rcu_launder_hist {
1672        long n_launders;
1673        unsigned long launder_gp_seq;
1674};
1675#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1676static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1677static unsigned long rcu_launder_gp_seq_start;
1678
1679static void rcu_torture_fwd_cb_hist(void)
1680{
1681        unsigned long gps;
1682        unsigned long gps_old;
1683        int i;
1684        int j;
1685
1686        for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1687                if (n_launders_hist[i].n_launders > 0)
1688                        break;
1689        pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1690                 __func__, jiffies - rcu_fwd_startat);
1691        gps_old = rcu_launder_gp_seq_start;
1692        for (j = 0; j <= i; j++) {
1693                gps = n_launders_hist[j].launder_gp_seq;
1694                pr_cont(" %ds/%d: %ld:%ld",
1695                        j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1696                        rcutorture_seq_diff(gps, gps_old));
1697                gps_old = gps;
1698        }
1699        pr_cont("\n");
1700}
1701
1702/* Callback function for continuous-flood RCU callbacks. */
1703static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1704{
1705        unsigned long flags;
1706        int i;
1707        struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1708        struct rcu_fwd_cb **rfcpp;
1709
1710        rfcp->rfc_next = NULL;
1711        rfcp->rfc_gps++;
1712        spin_lock_irqsave(&rcu_fwd_lock, flags);
1713        rfcpp = rcu_fwd_cb_tail;
1714        rcu_fwd_cb_tail = &rfcp->rfc_next;
1715        WRITE_ONCE(*rfcpp, rfcp);
1716        WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1717        i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1718        if (i >= ARRAY_SIZE(n_launders_hist))
1719                i = ARRAY_SIZE(n_launders_hist) - 1;
1720        n_launders_hist[i].n_launders++;
1721        n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1722        spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1723}
1724
1725// Give the scheduler a chance, even on nohz_full CPUs.
1726static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
1727{
1728        if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
1729                // Real call_rcu() floods hit userspace, so emulate that.
1730                if (need_resched() || (iter & 0xfff))
1731                        schedule();
1732        } else {
1733                // No userspace emulation: CB invocation throttles call_rcu()
1734                cond_resched();
1735        }
1736}
1737
1738/*
1739 * Free all callbacks on the rcu_fwd_cb_head list, either because the
1740 * test is over or because we hit an OOM event.
1741 */
1742static unsigned long rcu_torture_fwd_prog_cbfree(void)
1743{
1744        unsigned long flags;
1745        unsigned long freed = 0;
1746        struct rcu_fwd_cb *rfcp;
1747
1748        for (;;) {
1749                spin_lock_irqsave(&rcu_fwd_lock, flags);
1750                rfcp = rcu_fwd_cb_head;
1751                if (!rfcp) {
1752                        spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1753                        break;
1754                }
1755                rcu_fwd_cb_head = rfcp->rfc_next;
1756                if (!rcu_fwd_cb_head)
1757                        rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1758                spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1759                kfree(rfcp);
1760                freed++;
1761                rcu_torture_fwd_prog_cond_resched(freed);
1762        }
1763        return freed;
1764}
1765
1766/* Carry out need_resched()/cond_resched() forward-progress testing. */
1767static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1768{
1769        unsigned long cver;
1770        unsigned long dur;
1771        struct fwd_cb_state fcs;
1772        unsigned long gps;
1773        int idx;
1774        int sd;
1775        int sd4;
1776        bool selfpropcb = false;
1777        unsigned long stopat;
1778        static DEFINE_TORTURE_RANDOM(trs);
1779
1780        if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1781                init_rcu_head_on_stack(&fcs.rh);
1782                selfpropcb = true;
1783        }
1784
1785        /* Tight loop containing cond_resched(). */
1786        WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1787        cur_ops->sync(); /* Later readers see above write. */
1788        if  (selfpropcb) {
1789                WRITE_ONCE(fcs.stop, 0);
1790                cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1791        }
1792        cver = READ_ONCE(rcu_torture_current_version);
1793        gps = cur_ops->get_gp_seq();
1794        sd = cur_ops->stall_dur() + 1;
1795        sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1796        dur = sd4 + torture_random(&trs) % (sd - sd4);
1797        WRITE_ONCE(rcu_fwd_startat, jiffies);
1798        stopat = rcu_fwd_startat + dur;
1799        while (time_before(jiffies, stopat) &&
1800               !shutdown_time_arrived() &&
1801               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1802                idx = cur_ops->readlock();
1803                udelay(10);
1804                cur_ops->readunlock(idx);
1805                if (!fwd_progress_need_resched || need_resched())
1806                        rcu_torture_fwd_prog_cond_resched(1);
1807        }
1808        (*tested_tries)++;
1809        if (!time_before(jiffies, stopat) &&
1810            !shutdown_time_arrived() &&
1811            !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1812                (*tested)++;
1813                cver = READ_ONCE(rcu_torture_current_version) - cver;
1814                gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1815                WARN_ON(!cver && gps < 2);
1816                pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1817        }
1818        if (selfpropcb) {
1819                WRITE_ONCE(fcs.stop, 1);
1820                cur_ops->sync(); /* Wait for running CB to complete. */
1821                cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1822        }
1823
1824        if (selfpropcb) {
1825                WARN_ON(READ_ONCE(fcs.stop) != 2);
1826                destroy_rcu_head_on_stack(&fcs.rh);
1827        }
1828        schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
1829        WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1830}
1831
1832/* Carry out call_rcu() forward-progress testing. */
1833static void rcu_torture_fwd_prog_cr(void)
1834{
1835        unsigned long cver;
1836        unsigned long gps;
1837        int i;
1838        long n_launders;
1839        long n_launders_cb_snap;
1840        long n_launders_sa;
1841        long n_max_cbs;
1842        long n_max_gps;
1843        struct rcu_fwd_cb *rfcp;
1844        struct rcu_fwd_cb *rfcpn;
1845        unsigned long stopat;
1846        unsigned long stoppedat;
1847
1848        if (READ_ONCE(rcu_fwd_emergency_stop))
1849                return; /* Get out of the way quickly, no GP wait! */
1850        if (!cur_ops->call)
1851                return; /* Can't do call_rcu() fwd prog without ->call. */
1852
1853        /* Loop continuously posting RCU callbacks. */
1854        WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1855        cur_ops->sync(); /* Later readers see above write. */
1856        WRITE_ONCE(rcu_fwd_startat, jiffies);
1857        stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1858        n_launders = 0;
1859        n_launders_cb = 0;
1860        n_launders_sa = 0;
1861        n_max_cbs = 0;
1862        n_max_gps = 0;
1863        for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1864                n_launders_hist[i].n_launders = 0;
1865        cver = READ_ONCE(rcu_torture_current_version);
1866        gps = cur_ops->get_gp_seq();
1867        rcu_launder_gp_seq_start = gps;
1868        while (time_before(jiffies, stopat) &&
1869               !shutdown_time_arrived() &&
1870               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1871                rfcp = READ_ONCE(rcu_fwd_cb_head);
1872                rfcpn = NULL;
1873                if (rfcp)
1874                        rfcpn = READ_ONCE(rfcp->rfc_next);
1875                if (rfcpn) {
1876                        if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1877                            ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1878                                break;
1879                        rcu_fwd_cb_head = rfcpn;
1880                        n_launders++;
1881                        n_launders_sa++;
1882                } else {
1883                        rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1884                        if (WARN_ON_ONCE(!rfcp)) {
1885                                schedule_timeout_interruptible(1);
1886                                continue;
1887                        }
1888                        n_max_cbs++;
1889                        n_launders_sa = 0;
1890                        rfcp->rfc_gps = 0;
1891                }
1892                cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1893                rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
1894        }
1895        stoppedat = jiffies;
1896        n_launders_cb_snap = READ_ONCE(n_launders_cb);
1897        cver = READ_ONCE(rcu_torture_current_version) - cver;
1898        gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1899        cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1900        (void)rcu_torture_fwd_prog_cbfree();
1901
1902        if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
1903            !shutdown_time_arrived()) {
1904                WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1905                pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
1906                         __func__,
1907                         stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1908                         n_launders + n_max_cbs - n_launders_cb_snap,
1909                         n_launders, n_launders_sa,
1910                         n_max_gps, n_max_cbs, cver, gps);
1911                rcu_torture_fwd_cb_hist();
1912        }
1913        schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
1914        WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1915}
1916
1917
1918/*
1919 * OOM notifier, but this only prints diagnostic information for the
1920 * current forward-progress test.
1921 */
1922static int rcutorture_oom_notify(struct notifier_block *self,
1923                                 unsigned long notused, void *nfreed)
1924{
1925        WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1926             __func__);
1927        rcu_torture_fwd_cb_hist();
1928        rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
1929        WRITE_ONCE(rcu_fwd_emergency_stop, true);
1930        smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1931        pr_info("%s: Freed %lu RCU callbacks.\n",
1932                __func__, rcu_torture_fwd_prog_cbfree());
1933        rcu_barrier();
1934        pr_info("%s: Freed %lu RCU callbacks.\n",
1935                __func__, rcu_torture_fwd_prog_cbfree());
1936        rcu_barrier();
1937        pr_info("%s: Freed %lu RCU callbacks.\n",
1938                __func__, rcu_torture_fwd_prog_cbfree());
1939        smp_mb(); /* Frees before return to avoid redoing OOM. */
1940        (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1941        pr_info("%s returning after OOM processing.\n", __func__);
1942        return NOTIFY_OK;
1943}
1944
1945static struct notifier_block rcutorture_oom_nb = {
1946        .notifier_call = rcutorture_oom_notify
1947};
1948
1949/* Carry out grace-period forward-progress testing. */
1950static int rcu_torture_fwd_prog(void *args)
1951{
1952        int tested = 0;
1953        int tested_tries = 0;
1954
1955        VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1956        rcu_bind_current_to_nocb();
1957        if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1958                set_user_nice(current, MAX_NICE);
1959        do {
1960                schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1961                WRITE_ONCE(rcu_fwd_emergency_stop, false);
1962                register_oom_notifier(&rcutorture_oom_nb);
1963                rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1964                rcu_torture_fwd_prog_cr();
1965                unregister_oom_notifier(&rcutorture_oom_nb);
1966
1967                /* Avoid slow periods, better to test when busy. */
1968                stutter_wait("rcu_torture_fwd_prog");
1969        } while (!torture_must_stop());
1970        /* Short runs might not contain a valid forward-progress attempt. */
1971        WARN_ON(!tested && tested_tries >= 5);
1972        pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1973        torture_kthread_stopping("rcu_torture_fwd_prog");
1974        return 0;
1975}
1976
1977/* If forward-progress checking is requested and feasible, spawn the thread. */
1978static int __init rcu_torture_fwd_prog_init(void)
1979{
1980        if (!fwd_progress)
1981                return 0; /* Not requested, so don't do it. */
1982        if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1983            cur_ops == &rcu_busted_ops) {
1984                VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1985                return 0;
1986        }
1987        if (stall_cpu > 0) {
1988                VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1989                if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1990                        return -EINVAL; /* In module, can fail back to user. */
1991                WARN_ON(1); /* Make sure rcutorture notices conflict. */
1992                return 0;
1993        }
1994        if (fwd_progress_holdoff <= 0)
1995                fwd_progress_holdoff = 1;
1996        if (fwd_progress_div <= 0)
1997                fwd_progress_div = 4;
1998        return torture_create_kthread(rcu_torture_fwd_prog,
1999                                      NULL, fwd_prog_task);
2000}
2001
2002/* Callback function for RCU barrier testing. */
2003static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2004{
2005        atomic_inc(&barrier_cbs_invoked);
2006}
2007
2008/* kthread function to register callbacks used to test RCU barriers. */
2009static int rcu_torture_barrier_cbs(void *arg)
2010{
2011        long myid = (long)arg;
2012        bool lastphase = 0;
2013        bool newphase;
2014        struct rcu_head rcu;
2015
2016        init_rcu_head_on_stack(&rcu);
2017        VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2018        set_user_nice(current, MAX_NICE);
2019        do {
2020                wait_event(barrier_cbs_wq[myid],
2021                           (newphase =
2022                            smp_load_acquire(&barrier_phase)) != lastphase ||
2023                           torture_must_stop());
2024                lastphase = newphase;
2025                if (torture_must_stop())
2026                        break;
2027                /*
2028                 * The above smp_load_acquire() ensures barrier_phase load
2029                 * is ordered before the following ->call().
2030                 */
2031                local_irq_disable(); /* Just to test no-irq call_rcu(). */
2032                cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2033                local_irq_enable();
2034                if (atomic_dec_and_test(&barrier_cbs_count))
2035                        wake_up(&barrier_wq);
2036        } while (!torture_must_stop());
2037        if (cur_ops->cb_barrier != NULL)
2038                cur_ops->cb_barrier();
2039        destroy_rcu_head_on_stack(&rcu);
2040        torture_kthread_stopping("rcu_torture_barrier_cbs");
2041        return 0;
2042}
2043
2044/* kthread function to drive and coordinate RCU barrier testing. */
2045static int rcu_torture_barrier(void *arg)
2046{
2047        int i;
2048
2049        VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2050        do {
2051                atomic_set(&barrier_cbs_invoked, 0);
2052                atomic_set(&barrier_cbs_count, n_barrier_cbs);
2053                /* Ensure barrier_phase ordered after prior assignments. */
2054                smp_store_release(&barrier_phase, !barrier_phase);
2055                for (i = 0; i < n_barrier_cbs; i++)
2056                        wake_up(&barrier_cbs_wq[i]);
2057                wait_event(barrier_wq,
2058                           atomic_read(&barrier_cbs_count) == 0 ||
2059                           torture_must_stop());
2060                if (torture_must_stop())
2061                        break;
2062                n_barrier_attempts++;
2063                cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2064                if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2065                        n_rcu_torture_barrier_error++;
2066                        pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2067                               atomic_read(&barrier_cbs_invoked),
2068                               n_barrier_cbs);
2069                        WARN_ON_ONCE(1);
2070                } else {
2071                        n_barrier_successes++;
2072                }
2073                schedule_timeout_interruptible(HZ / 10);
2074        } while (!torture_must_stop());
2075        torture_kthread_stopping("rcu_torture_barrier");
2076        return 0;
2077}
2078
2079/* Initialize RCU barrier testing. */
2080static int rcu_torture_barrier_init(void)
2081{
2082        int i;
2083        int ret;
2084
2085        if (n_barrier_cbs <= 0)
2086                return 0;
2087        if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2088                pr_alert("%s" TORTURE_FLAG
2089                         " Call or barrier ops missing for %s,\n",
2090                         torture_type, cur_ops->name);
2091                pr_alert("%s" TORTURE_FLAG
2092                         " RCU barrier testing omitted from run.\n",
2093                         torture_type);
2094                return 0;
2095        }
2096        atomic_set(&barrier_cbs_count, 0);
2097        atomic_set(&barrier_cbs_invoked, 0);
2098        barrier_cbs_tasks =
2099                kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2100                        GFP_KERNEL);
2101        barrier_cbs_wq =
2102                kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2103        if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2104                return -ENOMEM;
2105        for (i = 0; i < n_barrier_cbs; i++) {
2106                init_waitqueue_head(&barrier_cbs_wq[i]);
2107                ret = torture_create_kthread(rcu_torture_barrier_cbs,
2108                                             (void *)(long)i,
2109                                             barrier_cbs_tasks[i]);
2110                if (ret)
2111                        return ret;
2112        }
2113        return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2114}
2115
2116/* Clean up after RCU barrier testing. */
2117static void rcu_torture_barrier_cleanup(void)
2118{
2119        int i;
2120
2121        torture_stop_kthread(rcu_torture_barrier, barrier_task);
2122        if (barrier_cbs_tasks != NULL) {
2123                for (i = 0; i < n_barrier_cbs; i++)
2124                        torture_stop_kthread(rcu_torture_barrier_cbs,
2125                                             barrier_cbs_tasks[i]);
2126                kfree(barrier_cbs_tasks);
2127                barrier_cbs_tasks = NULL;
2128        }
2129        if (barrier_cbs_wq != NULL) {
2130                kfree(barrier_cbs_wq);
2131                barrier_cbs_wq = NULL;
2132        }
2133}
2134
2135static bool rcu_torture_can_boost(void)
2136{
2137        static int boost_warn_once;
2138        int prio;
2139
2140        if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2141                return false;
2142
2143        prio = rcu_get_gp_kthreads_prio();
2144        if (!prio)
2145                return false;
2146
2147        if (prio < 2) {
2148                if (boost_warn_once  == 1)
2149                        return false;
2150
2151                pr_alert("%s: WARN: RCU kthread priority too low to test boosting.  Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
2152                boost_warn_once = 1;
2153                return false;
2154        }
2155
2156        return true;
2157}
2158
2159static enum cpuhp_state rcutor_hp;
2160
2161static void
2162rcu_torture_cleanup(void)
2163{
2164        int firsttime;
2165        int flags = 0;
2166        unsigned long gp_seq = 0;
2167        int i;
2168
2169        if (torture_cleanup_begin()) {
2170                if (cur_ops->cb_barrier != NULL)
2171                        cur_ops->cb_barrier();
2172                return;
2173        }
2174        if (!cur_ops) {
2175                torture_cleanup_end();
2176                return;
2177        }
2178
2179        show_rcu_gp_kthreads();
2180        rcu_torture_barrier_cleanup();
2181        torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2182        torture_stop_kthread(rcu_torture_stall, stall_task);
2183        torture_stop_kthread(rcu_torture_writer, writer_task);
2184
2185        if (reader_tasks) {
2186                for (i = 0; i < nrealreaders; i++)
2187                        torture_stop_kthread(rcu_torture_reader,
2188                                             reader_tasks[i]);
2189                kfree(reader_tasks);
2190        }
2191        rcu_torture_current = NULL;
2192
2193        if (fakewriter_tasks) {
2194                for (i = 0; i < nfakewriters; i++) {
2195                        torture_stop_kthread(rcu_torture_fakewriter,
2196                                             fakewriter_tasks[i]);
2197                }
2198                kfree(fakewriter_tasks);
2199                fakewriter_tasks = NULL;
2200        }
2201
2202        rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2203        srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2204        pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2205                 cur_ops->name, gp_seq, flags);
2206        torture_stop_kthread(rcu_torture_stats, stats_task);
2207        torture_stop_kthread(rcu_torture_fqs, fqs_task);
2208        if (rcu_torture_can_boost())
2209                cpuhp_remove_state(rcutor_hp);
2210
2211        /*
2212         * Wait for all RCU callbacks to fire, then do torture-type-specific
2213         * cleanup operations.
2214         */
2215        if (cur_ops->cb_barrier != NULL)
2216                cur_ops->cb_barrier();
2217        if (cur_ops->cleanup != NULL)
2218                cur_ops->cleanup();
2219
2220        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2221
2222        if (err_segs_recorded) {
2223                pr_alert("Failure/close-call rcutorture reader segments:\n");
2224                if (rt_read_nsegs == 0)
2225                        pr_alert("\t: No segments recorded!!!\n");
2226                firsttime = 1;
2227                for (i = 0; i < rt_read_nsegs; i++) {
2228                        pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2229                        if (err_segs[i].rt_delay_jiffies != 0) {
2230                                pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2231                                        err_segs[i].rt_delay_jiffies);
2232                                firsttime = 0;
2233                        }
2234                        if (err_segs[i].rt_delay_ms != 0) {
2235                                pr_cont("%s%ldms", firsttime ? "" : "+",
2236                                        err_segs[i].rt_delay_ms);
2237                                firsttime = 0;
2238                        }
2239                        if (err_segs[i].rt_delay_us != 0) {
2240                                pr_cont("%s%ldus", firsttime ? "" : "+",
2241                                        err_segs[i].rt_delay_us);
2242                                firsttime = 0;
2243                        }
2244                        pr_cont("%s\n",
2245                                err_segs[i].rt_preempted ? "preempted" : "");
2246
2247                }
2248        }
2249        if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2250                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2251        else if (torture_onoff_failures())
2252                rcu_torture_print_module_parms(cur_ops,
2253                                               "End of test: RCU_HOTPLUG");
2254        else
2255                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2256        torture_cleanup_end();
2257}
2258
2259#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2260static void rcu_torture_leak_cb(struct rcu_head *rhp)
2261{
2262}
2263
2264static void rcu_torture_err_cb(struct rcu_head *rhp)
2265{
2266        /*
2267         * This -might- happen due to race conditions, but is unlikely.
2268         * The scenario that leads to this happening is that the
2269         * first of the pair of duplicate callbacks is queued,
2270         * someone else starts a grace period that includes that
2271         * callback, then the second of the pair must wait for the
2272         * next grace period.  Unlikely, but can happen.  If it
2273         * does happen, the debug-objects subsystem won't have splatted.
2274         */
2275        pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2276}
2277#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2278
2279/*
2280 * Verify that double-free causes debug-objects to complain, but only
2281 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2282 * cannot be carried out.
2283 */
2284static void rcu_test_debug_objects(void)
2285{
2286#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2287        struct rcu_head rh1;
2288        struct rcu_head rh2;
2289
2290        init_rcu_head_on_stack(&rh1);
2291        init_rcu_head_on_stack(&rh2);
2292        pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2293
2294        /* Try to queue the rh2 pair of callbacks for the same grace period. */
2295        preempt_disable(); /* Prevent preemption from interrupting test. */
2296        rcu_read_lock(); /* Make it impossible to finish a grace period. */
2297        call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2298        local_irq_disable(); /* Make it harder to start a new grace period. */
2299        call_rcu(&rh2, rcu_torture_leak_cb);
2300        call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2301        local_irq_enable();
2302        rcu_read_unlock();
2303        preempt_enable();
2304
2305        /* Wait for them all to get done so we can safely return. */
2306        rcu_barrier();
2307        pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2308        destroy_rcu_head_on_stack(&rh1);
2309        destroy_rcu_head_on_stack(&rh2);
2310#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2311        pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2312#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2313}
2314
2315static void rcutorture_sync(void)
2316{
2317        static unsigned long n;
2318
2319        if (cur_ops->sync && !(++n & 0xfff))
2320                cur_ops->sync();
2321}
2322
2323static int __init
2324rcu_torture_init(void)
2325{
2326        long i;
2327        int cpu;
2328        int firsterr = 0;
2329        static struct rcu_torture_ops *torture_ops[] = {
2330                &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2331                &busted_srcud_ops, &tasks_ops, &trivial_ops,
2332        };
2333
2334        if (!torture_init_begin(torture_type, verbose))
2335                return -EBUSY;
2336
2337        /* Process args and tell the world that the torturer is on the job. */
2338        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2339                cur_ops = torture_ops[i];
2340                if (strcmp(torture_type, cur_ops->name) == 0)
2341                        break;
2342        }
2343        if (i == ARRAY_SIZE(torture_ops)) {
2344                pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2345                         torture_type);
2346                pr_alert("rcu-torture types:");
2347                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2348                        pr_cont(" %s", torture_ops[i]->name);
2349                pr_cont("\n");
2350                WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2351                firsterr = -EINVAL;
2352                cur_ops = NULL;
2353                goto unwind;
2354        }
2355        if (cur_ops->fqs == NULL && fqs_duration != 0) {
2356                pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2357                fqs_duration = 0;
2358        }
2359        if (cur_ops->init)
2360                cur_ops->init();
2361
2362        if (nreaders >= 0) {
2363                nrealreaders = nreaders;
2364        } else {
2365                nrealreaders = num_online_cpus() - 2 - nreaders;
2366                if (nrealreaders <= 0)
2367                        nrealreaders = 1;
2368        }
2369        rcu_torture_print_module_parms(cur_ops, "Start of test");
2370
2371        /* Set up the freelist. */
2372
2373        INIT_LIST_HEAD(&rcu_torture_freelist);
2374        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2375                rcu_tortures[i].rtort_mbtest = 0;
2376                list_add_tail(&rcu_tortures[i].rtort_free,
2377                              &rcu_torture_freelist);
2378        }
2379
2380        /* Initialize the statistics so that each run gets its own numbers. */
2381
2382        rcu_torture_current = NULL;
2383        rcu_torture_current_version = 0;
2384        atomic_set(&n_rcu_torture_alloc, 0);
2385        atomic_set(&n_rcu_torture_alloc_fail, 0);
2386        atomic_set(&n_rcu_torture_free, 0);
2387        atomic_set(&n_rcu_torture_mberror, 0);
2388        atomic_set(&n_rcu_torture_error, 0);
2389        n_rcu_torture_barrier_error = 0;
2390        n_rcu_torture_boost_ktrerror = 0;
2391        n_rcu_torture_boost_rterror = 0;
2392        n_rcu_torture_boost_failure = 0;
2393        n_rcu_torture_boosts = 0;
2394        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2395                atomic_set(&rcu_torture_wcount[i], 0);
2396        for_each_possible_cpu(cpu) {
2397                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2398                        per_cpu(rcu_torture_count, cpu)[i] = 0;
2399                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
2400                }
2401        }
2402        err_segs_recorded = 0;
2403        rt_read_nsegs = 0;
2404
2405        /* Start up the kthreads. */
2406
2407        firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2408                                          writer_task);
2409        if (firsterr)
2410                goto unwind;
2411        if (nfakewriters > 0) {
2412                fakewriter_tasks = kcalloc(nfakewriters,
2413                                           sizeof(fakewriter_tasks[0]),
2414                                           GFP_KERNEL);
2415                if (fakewriter_tasks == NULL) {
2416                        VERBOSE_TOROUT_ERRSTRING("out of memory");
2417                        firsterr = -ENOMEM;
2418                        goto unwind;
2419                }
2420        }
2421        for (i = 0; i < nfakewriters; i++) {
2422                firsterr = torture_create_kthread(rcu_torture_fakewriter,
2423                                                  NULL, fakewriter_tasks[i]);
2424                if (firsterr)
2425                        goto unwind;
2426        }
2427        reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2428                               GFP_KERNEL);
2429        if (reader_tasks == NULL) {
2430                VERBOSE_TOROUT_ERRSTRING("out of memory");
2431                firsterr = -ENOMEM;
2432                goto unwind;
2433        }
2434        for (i = 0; i < nrealreaders; i++) {
2435                firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2436                                                  reader_tasks[i]);
2437                if (firsterr)
2438                        goto unwind;
2439        }
2440        if (stat_interval > 0) {
2441                firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2442                                                  stats_task);
2443                if (firsterr)
2444                        goto unwind;
2445        }
2446        if (test_no_idle_hz && shuffle_interval > 0) {
2447                firsterr = torture_shuffle_init(shuffle_interval * HZ);
2448                if (firsterr)
2449                        goto unwind;
2450        }
2451        if (stutter < 0)
2452                stutter = 0;
2453        if (stutter) {
2454                int t;
2455
2456                t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
2457                firsterr = torture_stutter_init(stutter * HZ, t);
2458                if (firsterr)
2459                        goto unwind;
2460        }
2461        if (fqs_duration < 0)
2462                fqs_duration = 0;
2463        if (fqs_duration) {
2464                /* Create the fqs thread */
2465                firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2466                                                  fqs_task);
2467                if (firsterr)
2468                        goto unwind;
2469        }
2470        if (test_boost_interval < 1)
2471                test_boost_interval = 1;
2472        if (test_boost_duration < 2)
2473                test_boost_duration = 2;
2474        if (rcu_torture_can_boost()) {
2475
2476                boost_starttime = jiffies + test_boost_interval * HZ;
2477
2478                firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2479                                             rcutorture_booster_init,
2480                                             rcutorture_booster_cleanup);
2481                if (firsterr < 0)
2482                        goto unwind;
2483                rcutor_hp = firsterr;
2484        }
2485        shutdown_jiffies = jiffies + shutdown_secs * HZ;
2486        firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2487        if (firsterr)
2488                goto unwind;
2489        firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2490                                      rcutorture_sync);
2491        if (firsterr)
2492                goto unwind;
2493        firsterr = rcu_torture_stall_init();
2494        if (firsterr)
2495                goto unwind;
2496        firsterr = rcu_torture_fwd_prog_init();
2497        if (firsterr)
2498                goto unwind;
2499        firsterr = rcu_torture_barrier_init();
2500        if (firsterr)
2501                goto unwind;
2502        if (object_debug)
2503                rcu_test_debug_objects();
2504        torture_init_end();
2505        return 0;
2506
2507unwind:
2508        torture_init_end();
2509        rcu_torture_cleanup();
2510        return firsterr;
2511}
2512
2513module_init(rcu_torture_init);
2514module_exit(rcu_torture_cleanup);
2515