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.rst
  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_wait.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#include <linux/tick.h>
  48#include <linux/rcupdate_trace.h>
  49
  50#include "rcu.h"
  51
  52MODULE_LICENSE("GPL");
  53MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  54
  55/* Bits for ->extendables field, extendables param, and related definitions. */
  56#define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  57#define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  58#define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  59#define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  60#define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  61#define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  62#define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  63#define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  64#define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  65#define RCUTORTURE_MAX_EXTEND    \
  66        (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  67         RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  68#define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  69                                        /* Must be power of two minus one. */
  70#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  71
  72torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  73              "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  74torture_param(int, fqs_duration, 0,
  75              "Duration of fqs bursts (us), 0 to disable");
  76torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  77torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  78torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  79torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  80torture_param(int, fwd_progress_holdoff, 60,
  81              "Time between forward-progress tests (s)");
  82torture_param(bool, fwd_progress_need_resched, 1,
  83              "Hide cond_resched() behind need_resched()");
  84torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  85torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  86torture_param(bool, gp_normal, false,
  87             "Use normal (non-expedited) GP wait primitives");
  88torture_param(bool, gp_poll, false, "Use polling GP wait primitives");
  89torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  90torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  91torture_param(int, leakpointer, 0, "Leak pointer dereferences from readers");
  92torture_param(int, n_barrier_cbs, 0,
  93             "# of callbacks/kthreads for barrier testing");
  94torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  95torture_param(int, nreaders, -1, "Number of RCU reader threads");
  96torture_param(int, object_debug, 0,
  97             "Enable debug-object double call_rcu() testing");
  98torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  99torture_param(int, onoff_interval, 0,
 100             "Time between CPU hotplugs (jiffies), 0=disable");
 101torture_param(int, nocbs_nthreads, 0, "Number of NOCB toggle threads, 0 to disable");
 102torture_param(int, nocbs_toggle, 1000, "Time between toggling nocb state (ms)");
 103torture_param(int, read_exit_delay, 13,
 104              "Delay between read-then-exit episodes (s)");
 105torture_param(int, read_exit_burst, 16,
 106              "# of read-then-exit bursts per episode, zero to disable");
 107torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 108torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 109torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 110torture_param(int, stall_cpu_holdoff, 10,
 111             "Time to wait before starting stall (s).");
 112torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 113torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
 114torture_param(int, stall_gp_kthread, 0,
 115              "Grace-period kthread stall duration (s).");
 116torture_param(int, stat_interval, 60,
 117             "Number of seconds between stats printk()s");
 118torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 119torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 120torture_param(int, test_boost_duration, 4,
 121             "Duration of each boost test, seconds.");
 122torture_param(int, test_boost_interval, 7,
 123             "Interval between boost tests, seconds.");
 124torture_param(bool, test_no_idle_hz, true,
 125             "Test support for tickless idle CPUs");
 126torture_param(int, verbose, 1,
 127             "Enable verbose debugging printk()s");
 128
 129static char *torture_type = "rcu";
 130module_param(torture_type, charp, 0444);
 131MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 132
 133static int nrealnocbers;
 134static int nrealreaders;
 135static struct task_struct *writer_task;
 136static struct task_struct **fakewriter_tasks;
 137static struct task_struct **reader_tasks;
 138static struct task_struct **nocb_tasks;
 139static struct task_struct *stats_task;
 140static struct task_struct *fqs_task;
 141static struct task_struct *boost_tasks[NR_CPUS];
 142static struct task_struct *stall_task;
 143static struct task_struct *fwd_prog_task;
 144static struct task_struct **barrier_cbs_tasks;
 145static struct task_struct *barrier_task;
 146static struct task_struct *read_exit_task;
 147
 148#define RCU_TORTURE_PIPE_LEN 10
 149
 150// Mailbox-like structure to check RCU global memory ordering.
 151struct rcu_torture_reader_check {
 152        unsigned long rtc_myloops;
 153        int rtc_chkrdr;
 154        unsigned long rtc_chkloops;
 155        int rtc_ready;
 156        struct rcu_torture_reader_check *rtc_assigner;
 157} ____cacheline_internodealigned_in_smp;
 158
 159// Update-side data structure used to check RCU readers.
 160struct rcu_torture {
 161        struct rcu_head rtort_rcu;
 162        int rtort_pipe_count;
 163        struct list_head rtort_free;
 164        int rtort_mbtest;
 165        struct rcu_torture_reader_check *rtort_chkp;
 166};
 167
 168static LIST_HEAD(rcu_torture_freelist);
 169static struct rcu_torture __rcu *rcu_torture_current;
 170static unsigned long rcu_torture_current_version;
 171static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 172static DEFINE_SPINLOCK(rcu_torture_lock);
 173static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 174static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 175static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 176static struct rcu_torture_reader_check *rcu_torture_reader_mbchk;
 177static atomic_t n_rcu_torture_alloc;
 178static atomic_t n_rcu_torture_alloc_fail;
 179static atomic_t n_rcu_torture_free;
 180static atomic_t n_rcu_torture_mberror;
 181static atomic_t n_rcu_torture_mbchk_fail;
 182static atomic_t n_rcu_torture_mbchk_tries;
 183static atomic_t n_rcu_torture_error;
 184static long n_rcu_torture_barrier_error;
 185static long n_rcu_torture_boost_ktrerror;
 186static long n_rcu_torture_boost_rterror;
 187static long n_rcu_torture_boost_failure;
 188static long n_rcu_torture_boosts;
 189static atomic_long_t n_rcu_torture_timers;
 190static long n_barrier_attempts;
 191static long n_barrier_successes; /* did rcu_barrier test succeed? */
 192static unsigned long n_read_exits;
 193static struct list_head rcu_torture_removed;
 194static unsigned long shutdown_jiffies;
 195static unsigned long start_gp_seq;
 196static atomic_long_t n_nocb_offload;
 197static atomic_long_t n_nocb_deoffload;
 198
 199static int rcu_torture_writer_state;
 200#define RTWS_FIXED_DELAY        0
 201#define RTWS_DELAY              1
 202#define RTWS_REPLACE            2
 203#define RTWS_DEF_FREE           3
 204#define RTWS_EXP_SYNC           4
 205#define RTWS_COND_GET           5
 206#define RTWS_COND_SYNC          6
 207#define RTWS_POLL_GET           7
 208#define RTWS_POLL_WAIT          8
 209#define RTWS_SYNC               9
 210#define RTWS_STUTTER            10
 211#define RTWS_STOPPING           11
 212static const char * const rcu_torture_writer_state_names[] = {
 213        "RTWS_FIXED_DELAY",
 214        "RTWS_DELAY",
 215        "RTWS_REPLACE",
 216        "RTWS_DEF_FREE",
 217        "RTWS_EXP_SYNC",
 218        "RTWS_COND_GET",
 219        "RTWS_COND_SYNC",
 220        "RTWS_POLL_GET",
 221        "RTWS_POLL_WAIT",
 222        "RTWS_SYNC",
 223        "RTWS_STUTTER",
 224        "RTWS_STOPPING",
 225};
 226
 227/* Record reader segment types and duration for first failing read. */
 228struct rt_read_seg {
 229        int rt_readstate;
 230        unsigned long rt_delay_jiffies;
 231        unsigned long rt_delay_ms;
 232        unsigned long rt_delay_us;
 233        bool rt_preempted;
 234};
 235static int err_segs_recorded;
 236static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 237static int rt_read_nsegs;
 238
 239static const char *rcu_torture_writer_state_getname(void)
 240{
 241        unsigned int i = READ_ONCE(rcu_torture_writer_state);
 242
 243        if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 244                return "???";
 245        return rcu_torture_writer_state_names[i];
 246}
 247
 248#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 249#define rcu_can_boost() 1
 250#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 251#define rcu_can_boost() 0
 252#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 253
 254#ifdef CONFIG_RCU_TRACE
 255static u64 notrace rcu_trace_clock_local(void)
 256{
 257        u64 ts = trace_clock_local();
 258
 259        (void)do_div(ts, NSEC_PER_USEC);
 260        return ts;
 261}
 262#else /* #ifdef CONFIG_RCU_TRACE */
 263static u64 notrace rcu_trace_clock_local(void)
 264{
 265        return 0ULL;
 266}
 267#endif /* #else #ifdef CONFIG_RCU_TRACE */
 268
 269/*
 270 * Stop aggressive CPU-hog tests a bit before the end of the test in order
 271 * to avoid interfering with test shutdown.
 272 */
 273static bool shutdown_time_arrived(void)
 274{
 275        return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 276}
 277
 278static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 279static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 280                                        /*  and boost task create/destroy. */
 281static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 282static bool barrier_phase;              /* Test phase. */
 283static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 284static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 285static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 286
 287static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 288
 289/*
 290 * Allocate an element from the rcu_tortures pool.
 291 */
 292static struct rcu_torture *
 293rcu_torture_alloc(void)
 294{
 295        struct list_head *p;
 296
 297        spin_lock_bh(&rcu_torture_lock);
 298        if (list_empty(&rcu_torture_freelist)) {
 299                atomic_inc(&n_rcu_torture_alloc_fail);
 300                spin_unlock_bh(&rcu_torture_lock);
 301                return NULL;
 302        }
 303        atomic_inc(&n_rcu_torture_alloc);
 304        p = rcu_torture_freelist.next;
 305        list_del_init(p);
 306        spin_unlock_bh(&rcu_torture_lock);
 307        return container_of(p, struct rcu_torture, rtort_free);
 308}
 309
 310/*
 311 * Free an element to the rcu_tortures pool.
 312 */
 313static void
 314rcu_torture_free(struct rcu_torture *p)
 315{
 316        atomic_inc(&n_rcu_torture_free);
 317        spin_lock_bh(&rcu_torture_lock);
 318        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 319        spin_unlock_bh(&rcu_torture_lock);
 320}
 321
 322/*
 323 * Operations vector for selecting different types of tests.
 324 */
 325
 326struct rcu_torture_ops {
 327        int ttype;
 328        void (*init)(void);
 329        void (*cleanup)(void);
 330        int (*readlock)(void);
 331        void (*read_delay)(struct torture_random_state *rrsp,
 332                           struct rt_read_seg *rtrsp);
 333        void (*readunlock)(int idx);
 334        unsigned long (*get_gp_seq)(void);
 335        unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 336        void (*deferred_free)(struct rcu_torture *p);
 337        void (*sync)(void);
 338        void (*exp_sync)(void);
 339        unsigned long (*get_gp_state)(void);
 340        unsigned long (*start_gp_poll)(void);
 341        bool (*poll_gp_state)(unsigned long oldstate);
 342        void (*cond_sync)(unsigned long oldstate);
 343        call_rcu_func_t call;
 344        void (*cb_barrier)(void);
 345        void (*fqs)(void);
 346        void (*stats)(void);
 347        void (*gp_kthread_dbg)(void);
 348        int (*stall_dur)(void);
 349        int irq_capable;
 350        int can_boost;
 351        int extendables;
 352        int slow_gps;
 353        const char *name;
 354};
 355
 356static struct rcu_torture_ops *cur_ops;
 357
 358/*
 359 * Definitions for rcu torture testing.
 360 */
 361
 362static int rcu_torture_read_lock(void) __acquires(RCU)
 363{
 364        rcu_read_lock();
 365        return 0;
 366}
 367
 368static void
 369rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 370{
 371        unsigned long started;
 372        unsigned long completed;
 373        const unsigned long shortdelay_us = 200;
 374        unsigned long longdelay_ms = 300;
 375        unsigned long long ts;
 376
 377        /* We want a short delay sometimes to make a reader delay the grace
 378         * period, and we want a long delay occasionally to trigger
 379         * force_quiescent_state. */
 380
 381        if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
 382            !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 383                started = cur_ops->get_gp_seq();
 384                ts = rcu_trace_clock_local();
 385                if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 386                        longdelay_ms = 5; /* Avoid triggering BH limits. */
 387                mdelay(longdelay_ms);
 388                rtrsp->rt_delay_ms = longdelay_ms;
 389                completed = cur_ops->get_gp_seq();
 390                do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 391                                          started, completed);
 392        }
 393        if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 394                udelay(shortdelay_us);
 395                rtrsp->rt_delay_us = shortdelay_us;
 396        }
 397        if (!preempt_count() &&
 398            !(torture_random(rrsp) % (nrealreaders * 500))) {
 399                torture_preempt_schedule();  /* QS only if preemptible. */
 400                rtrsp->rt_preempted = true;
 401        }
 402}
 403
 404static void rcu_torture_read_unlock(int idx) __releases(RCU)
 405{
 406        rcu_read_unlock();
 407}
 408
 409/*
 410 * Update callback in the pipe.  This should be invoked after a grace period.
 411 */
 412static bool
 413rcu_torture_pipe_update_one(struct rcu_torture *rp)
 414{
 415        int i;
 416        struct rcu_torture_reader_check *rtrcp = READ_ONCE(rp->rtort_chkp);
 417
 418        if (rtrcp) {
 419                WRITE_ONCE(rp->rtort_chkp, NULL);
 420                smp_store_release(&rtrcp->rtc_ready, 1); // Pair with smp_load_acquire().
 421        }
 422        i = READ_ONCE(rp->rtort_pipe_count);
 423        if (i > RCU_TORTURE_PIPE_LEN)
 424                i = RCU_TORTURE_PIPE_LEN;
 425        atomic_inc(&rcu_torture_wcount[i]);
 426        WRITE_ONCE(rp->rtort_pipe_count, i + 1);
 427        if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 428                rp->rtort_mbtest = 0;
 429                return true;
 430        }
 431        return false;
 432}
 433
 434/*
 435 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 436 * primitives.
 437 */
 438static void
 439rcu_torture_pipe_update(struct rcu_torture *old_rp)
 440{
 441        struct rcu_torture *rp;
 442        struct rcu_torture *rp1;
 443
 444        if (old_rp)
 445                list_add(&old_rp->rtort_free, &rcu_torture_removed);
 446        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 447                if (rcu_torture_pipe_update_one(rp)) {
 448                        list_del(&rp->rtort_free);
 449                        rcu_torture_free(rp);
 450                }
 451        }
 452}
 453
 454static void
 455rcu_torture_cb(struct rcu_head *p)
 456{
 457        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 458
 459        if (torture_must_stop_irq()) {
 460                /* Test is ending, just drop callbacks on the floor. */
 461                /* The next initialization will pick up the pieces. */
 462                return;
 463        }
 464        if (rcu_torture_pipe_update_one(rp))
 465                rcu_torture_free(rp);
 466        else
 467                cur_ops->deferred_free(rp);
 468}
 469
 470static unsigned long rcu_no_completed(void)
 471{
 472        return 0;
 473}
 474
 475static void rcu_torture_deferred_free(struct rcu_torture *p)
 476{
 477        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 478}
 479
 480static void rcu_sync_torture_init(void)
 481{
 482        INIT_LIST_HEAD(&rcu_torture_removed);
 483}
 484
 485static struct rcu_torture_ops rcu_ops = {
 486        .ttype          = RCU_FLAVOR,
 487        .init           = rcu_sync_torture_init,
 488        .readlock       = rcu_torture_read_lock,
 489        .read_delay     = rcu_read_delay,
 490        .readunlock     = rcu_torture_read_unlock,
 491        .get_gp_seq     = rcu_get_gp_seq,
 492        .gp_diff        = rcu_seq_diff,
 493        .deferred_free  = rcu_torture_deferred_free,
 494        .sync           = synchronize_rcu,
 495        .exp_sync       = synchronize_rcu_expedited,
 496        .get_gp_state   = get_state_synchronize_rcu,
 497        .cond_sync      = cond_synchronize_rcu,
 498        .call           = call_rcu,
 499        .cb_barrier     = rcu_barrier,
 500        .fqs            = rcu_force_quiescent_state,
 501        .stats          = NULL,
 502        .gp_kthread_dbg = show_rcu_gp_kthreads,
 503        .stall_dur      = rcu_jiffies_till_stall_check,
 504        .irq_capable    = 1,
 505        .can_boost      = rcu_can_boost(),
 506        .extendables    = RCUTORTURE_MAX_EXTEND,
 507        .name           = "rcu"
 508};
 509
 510/*
 511 * Don't even think about trying any of these in real life!!!
 512 * The names includes "busted", and they really means it!
 513 * The only purpose of these functions is to provide a buggy RCU
 514 * implementation to make sure that rcutorture correctly emits
 515 * buggy-RCU error messages.
 516 */
 517static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 518{
 519        /* This is a deliberate bug for testing purposes only! */
 520        rcu_torture_cb(&p->rtort_rcu);
 521}
 522
 523static void synchronize_rcu_busted(void)
 524{
 525        /* This is a deliberate bug for testing purposes only! */
 526}
 527
 528static void
 529call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 530{
 531        /* This is a deliberate bug for testing purposes only! */
 532        func(head);
 533}
 534
 535static struct rcu_torture_ops rcu_busted_ops = {
 536        .ttype          = INVALID_RCU_FLAVOR,
 537        .init           = rcu_sync_torture_init,
 538        .readlock       = rcu_torture_read_lock,
 539        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 540        .readunlock     = rcu_torture_read_unlock,
 541        .get_gp_seq     = rcu_no_completed,
 542        .deferred_free  = rcu_busted_torture_deferred_free,
 543        .sync           = synchronize_rcu_busted,
 544        .exp_sync       = synchronize_rcu_busted,
 545        .call           = call_rcu_busted,
 546        .cb_barrier     = NULL,
 547        .fqs            = NULL,
 548        .stats          = NULL,
 549        .irq_capable    = 1,
 550        .name           = "busted"
 551};
 552
 553/*
 554 * Definitions for srcu torture testing.
 555 */
 556
 557DEFINE_STATIC_SRCU(srcu_ctl);
 558static struct srcu_struct srcu_ctld;
 559static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 560
 561static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 562{
 563        return srcu_read_lock(srcu_ctlp);
 564}
 565
 566static void
 567srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 568{
 569        long delay;
 570        const long uspertick = 1000000 / HZ;
 571        const long longdelay = 10;
 572
 573        /* We want there to be long-running readers, but not all the time. */
 574
 575        delay = torture_random(rrsp) %
 576                (nrealreaders * 2 * longdelay * uspertick);
 577        if (!delay && in_task()) {
 578                schedule_timeout_interruptible(longdelay);
 579                rtrsp->rt_delay_jiffies = longdelay;
 580        } else {
 581                rcu_read_delay(rrsp, rtrsp);
 582        }
 583}
 584
 585static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 586{
 587        srcu_read_unlock(srcu_ctlp, idx);
 588}
 589
 590static unsigned long srcu_torture_completed(void)
 591{
 592        return srcu_batches_completed(srcu_ctlp);
 593}
 594
 595static void srcu_torture_deferred_free(struct rcu_torture *rp)
 596{
 597        call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 598}
 599
 600static void srcu_torture_synchronize(void)
 601{
 602        synchronize_srcu(srcu_ctlp);
 603}
 604
 605static unsigned long srcu_torture_get_gp_state(void)
 606{
 607        return get_state_synchronize_srcu(srcu_ctlp);
 608}
 609
 610static unsigned long srcu_torture_start_gp_poll(void)
 611{
 612        return start_poll_synchronize_srcu(srcu_ctlp);
 613}
 614
 615static bool srcu_torture_poll_gp_state(unsigned long oldstate)
 616{
 617        return poll_state_synchronize_srcu(srcu_ctlp, oldstate);
 618}
 619
 620static void srcu_torture_call(struct rcu_head *head,
 621                              rcu_callback_t func)
 622{
 623        call_srcu(srcu_ctlp, head, func);
 624}
 625
 626static void srcu_torture_barrier(void)
 627{
 628        srcu_barrier(srcu_ctlp);
 629}
 630
 631static void srcu_torture_stats(void)
 632{
 633        srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 634}
 635
 636static void srcu_torture_synchronize_expedited(void)
 637{
 638        synchronize_srcu_expedited(srcu_ctlp);
 639}
 640
 641static struct rcu_torture_ops srcu_ops = {
 642        .ttype          = SRCU_FLAVOR,
 643        .init           = rcu_sync_torture_init,
 644        .readlock       = srcu_torture_read_lock,
 645        .read_delay     = srcu_read_delay,
 646        .readunlock     = srcu_torture_read_unlock,
 647        .get_gp_seq     = srcu_torture_completed,
 648        .deferred_free  = srcu_torture_deferred_free,
 649        .sync           = srcu_torture_synchronize,
 650        .exp_sync       = srcu_torture_synchronize_expedited,
 651        .get_gp_state   = srcu_torture_get_gp_state,
 652        .start_gp_poll  = srcu_torture_start_gp_poll,
 653        .poll_gp_state  = srcu_torture_poll_gp_state,
 654        .call           = srcu_torture_call,
 655        .cb_barrier     = srcu_torture_barrier,
 656        .stats          = srcu_torture_stats,
 657        .irq_capable    = 1,
 658        .name           = "srcu"
 659};
 660
 661static void srcu_torture_init(void)
 662{
 663        rcu_sync_torture_init();
 664        WARN_ON(init_srcu_struct(&srcu_ctld));
 665        srcu_ctlp = &srcu_ctld;
 666}
 667
 668static void srcu_torture_cleanup(void)
 669{
 670        cleanup_srcu_struct(&srcu_ctld);
 671        srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 672}
 673
 674/* As above, but dynamically allocated. */
 675static struct rcu_torture_ops srcud_ops = {
 676        .ttype          = SRCU_FLAVOR,
 677        .init           = srcu_torture_init,
 678        .cleanup        = srcu_torture_cleanup,
 679        .readlock       = srcu_torture_read_lock,
 680        .read_delay     = srcu_read_delay,
 681        .readunlock     = srcu_torture_read_unlock,
 682        .get_gp_seq     = srcu_torture_completed,
 683        .deferred_free  = srcu_torture_deferred_free,
 684        .sync           = srcu_torture_synchronize,
 685        .exp_sync       = srcu_torture_synchronize_expedited,
 686        .call           = srcu_torture_call,
 687        .cb_barrier     = srcu_torture_barrier,
 688        .stats          = srcu_torture_stats,
 689        .irq_capable    = 1,
 690        .name           = "srcud"
 691};
 692
 693/* As above, but broken due to inappropriate reader extension. */
 694static struct rcu_torture_ops busted_srcud_ops = {
 695        .ttype          = SRCU_FLAVOR,
 696        .init           = srcu_torture_init,
 697        .cleanup        = srcu_torture_cleanup,
 698        .readlock       = srcu_torture_read_lock,
 699        .read_delay     = rcu_read_delay,
 700        .readunlock     = srcu_torture_read_unlock,
 701        .get_gp_seq     = srcu_torture_completed,
 702        .deferred_free  = srcu_torture_deferred_free,
 703        .sync           = srcu_torture_synchronize,
 704        .exp_sync       = srcu_torture_synchronize_expedited,
 705        .call           = srcu_torture_call,
 706        .cb_barrier     = srcu_torture_barrier,
 707        .stats          = srcu_torture_stats,
 708        .irq_capable    = 1,
 709        .extendables    = RCUTORTURE_MAX_EXTEND,
 710        .name           = "busted_srcud"
 711};
 712
 713/*
 714 * Definitions for RCU-tasks torture testing.
 715 */
 716
 717static int tasks_torture_read_lock(void)
 718{
 719        return 0;
 720}
 721
 722static void tasks_torture_read_unlock(int idx)
 723{
 724}
 725
 726static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 727{
 728        call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 729}
 730
 731static void synchronize_rcu_mult_test(void)
 732{
 733        synchronize_rcu_mult(call_rcu_tasks, call_rcu);
 734}
 735
 736static struct rcu_torture_ops tasks_ops = {
 737        .ttype          = RCU_TASKS_FLAVOR,
 738        .init           = rcu_sync_torture_init,
 739        .readlock       = tasks_torture_read_lock,
 740        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 741        .readunlock     = tasks_torture_read_unlock,
 742        .get_gp_seq     = rcu_no_completed,
 743        .deferred_free  = rcu_tasks_torture_deferred_free,
 744        .sync           = synchronize_rcu_tasks,
 745        .exp_sync       = synchronize_rcu_mult_test,
 746        .call           = call_rcu_tasks,
 747        .cb_barrier     = rcu_barrier_tasks,
 748        .gp_kthread_dbg = show_rcu_tasks_classic_gp_kthread,
 749        .fqs            = NULL,
 750        .stats          = NULL,
 751        .irq_capable    = 1,
 752        .slow_gps       = 1,
 753        .name           = "tasks"
 754};
 755
 756/*
 757 * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 758 * This implementation does not necessarily work well with CPU hotplug.
 759 */
 760
 761static void synchronize_rcu_trivial(void)
 762{
 763        int cpu;
 764
 765        for_each_online_cpu(cpu) {
 766                rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 767                WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 768        }
 769}
 770
 771static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 772{
 773        preempt_disable();
 774        return 0;
 775}
 776
 777static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 778{
 779        preempt_enable();
 780}
 781
 782static struct rcu_torture_ops trivial_ops = {
 783        .ttype          = RCU_TRIVIAL_FLAVOR,
 784        .init           = rcu_sync_torture_init,
 785        .readlock       = rcu_torture_read_lock_trivial,
 786        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 787        .readunlock     = rcu_torture_read_unlock_trivial,
 788        .get_gp_seq     = rcu_no_completed,
 789        .sync           = synchronize_rcu_trivial,
 790        .exp_sync       = synchronize_rcu_trivial,
 791        .fqs            = NULL,
 792        .stats          = NULL,
 793        .irq_capable    = 1,
 794        .name           = "trivial"
 795};
 796
 797/*
 798 * Definitions for rude RCU-tasks torture testing.
 799 */
 800
 801static void rcu_tasks_rude_torture_deferred_free(struct rcu_torture *p)
 802{
 803        call_rcu_tasks_rude(&p->rtort_rcu, rcu_torture_cb);
 804}
 805
 806static struct rcu_torture_ops tasks_rude_ops = {
 807        .ttype          = RCU_TASKS_RUDE_FLAVOR,
 808        .init           = rcu_sync_torture_init,
 809        .readlock       = rcu_torture_read_lock_trivial,
 810        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 811        .readunlock     = rcu_torture_read_unlock_trivial,
 812        .get_gp_seq     = rcu_no_completed,
 813        .deferred_free  = rcu_tasks_rude_torture_deferred_free,
 814        .sync           = synchronize_rcu_tasks_rude,
 815        .exp_sync       = synchronize_rcu_tasks_rude,
 816        .call           = call_rcu_tasks_rude,
 817        .cb_barrier     = rcu_barrier_tasks_rude,
 818        .gp_kthread_dbg = show_rcu_tasks_rude_gp_kthread,
 819        .fqs            = NULL,
 820        .stats          = NULL,
 821        .irq_capable    = 1,
 822        .name           = "tasks-rude"
 823};
 824
 825/*
 826 * Definitions for tracing RCU-tasks torture testing.
 827 */
 828
 829static int tasks_tracing_torture_read_lock(void)
 830{
 831        rcu_read_lock_trace();
 832        return 0;
 833}
 834
 835static void tasks_tracing_torture_read_unlock(int idx)
 836{
 837        rcu_read_unlock_trace();
 838}
 839
 840static void rcu_tasks_tracing_torture_deferred_free(struct rcu_torture *p)
 841{
 842        call_rcu_tasks_trace(&p->rtort_rcu, rcu_torture_cb);
 843}
 844
 845static struct rcu_torture_ops tasks_tracing_ops = {
 846        .ttype          = RCU_TASKS_TRACING_FLAVOR,
 847        .init           = rcu_sync_torture_init,
 848        .readlock       = tasks_tracing_torture_read_lock,
 849        .read_delay     = srcu_read_delay,  /* just reuse srcu's version. */
 850        .readunlock     = tasks_tracing_torture_read_unlock,
 851        .get_gp_seq     = rcu_no_completed,
 852        .deferred_free  = rcu_tasks_tracing_torture_deferred_free,
 853        .sync           = synchronize_rcu_tasks_trace,
 854        .exp_sync       = synchronize_rcu_tasks_trace,
 855        .call           = call_rcu_tasks_trace,
 856        .cb_barrier     = rcu_barrier_tasks_trace,
 857        .gp_kthread_dbg = show_rcu_tasks_trace_gp_kthread,
 858        .fqs            = NULL,
 859        .stats          = NULL,
 860        .irq_capable    = 1,
 861        .slow_gps       = 1,
 862        .name           = "tasks-tracing"
 863};
 864
 865static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 866{
 867        if (!cur_ops->gp_diff)
 868                return new - old;
 869        return cur_ops->gp_diff(new, old);
 870}
 871
 872static bool __maybe_unused torturing_tasks(void)
 873{
 874        return cur_ops == &tasks_ops || cur_ops == &tasks_rude_ops;
 875}
 876
 877/*
 878 * RCU torture priority-boost testing.  Runs one real-time thread per
 879 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 880 * spinning waiting for them to be invoked.  If a given callback takes
 881 * too long to be invoked, we assume that priority inversion has occurred.
 882 */
 883
 884struct rcu_boost_inflight {
 885        struct rcu_head rcu;
 886        int inflight;
 887};
 888
 889static void rcu_torture_boost_cb(struct rcu_head *head)
 890{
 891        struct rcu_boost_inflight *rbip =
 892                container_of(head, struct rcu_boost_inflight, rcu);
 893
 894        /* Ensure RCU-core accesses precede clearing ->inflight */
 895        smp_store_release(&rbip->inflight, 0);
 896}
 897
 898static int old_rt_runtime = -1;
 899
 900static void rcu_torture_disable_rt_throttle(void)
 901{
 902        /*
 903         * Disable RT throttling so that rcutorture's boost threads don't get
 904         * throttled. Only possible if rcutorture is built-in otherwise the
 905         * user should manually do this by setting the sched_rt_period_us and
 906         * sched_rt_runtime sysctls.
 907         */
 908        if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 909                return;
 910
 911        old_rt_runtime = sysctl_sched_rt_runtime;
 912        sysctl_sched_rt_runtime = -1;
 913}
 914
 915static void rcu_torture_enable_rt_throttle(void)
 916{
 917        if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 918                return;
 919
 920        sysctl_sched_rt_runtime = old_rt_runtime;
 921        old_rt_runtime = -1;
 922}
 923
 924static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 925{
 926        if (end - start > test_boost_duration * HZ - HZ / 2) {
 927                VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 928                n_rcu_torture_boost_failure++;
 929
 930                return true; /* failed */
 931        }
 932
 933        return false; /* passed */
 934}
 935
 936static int rcu_torture_boost(void *arg)
 937{
 938        unsigned long call_rcu_time;
 939        unsigned long endtime;
 940        unsigned long oldstarttime;
 941        struct rcu_boost_inflight rbi = { .inflight = 0 };
 942        struct sched_param sp;
 943
 944        VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 945
 946        /* Set real-time priority. */
 947        sp.sched_priority = 1;
 948        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 949                VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 950                n_rcu_torture_boost_rterror++;
 951        }
 952
 953        init_rcu_head_on_stack(&rbi.rcu);
 954        /* Each pass through the following loop does one boost-test cycle. */
 955        do {
 956                /* Track if the test failed already in this test interval? */
 957                bool failed = false;
 958
 959                /* Increment n_rcu_torture_boosts once per boost-test */
 960                while (!kthread_should_stop()) {
 961                        if (mutex_trylock(&boost_mutex)) {
 962                                n_rcu_torture_boosts++;
 963                                mutex_unlock(&boost_mutex);
 964                                break;
 965                        }
 966                        schedule_timeout_uninterruptible(1);
 967                }
 968                if (kthread_should_stop())
 969                        goto checkwait;
 970
 971                /* Wait for the next test interval. */
 972                oldstarttime = boost_starttime;
 973                while (time_before(jiffies, oldstarttime)) {
 974                        schedule_timeout_interruptible(oldstarttime - jiffies);
 975                        if (stutter_wait("rcu_torture_boost"))
 976                                sched_set_fifo_low(current);
 977                        if (torture_must_stop())
 978                                goto checkwait;
 979                }
 980
 981                /* Do one boost-test interval. */
 982                endtime = oldstarttime + test_boost_duration * HZ;
 983                call_rcu_time = jiffies;
 984                while (time_before(jiffies, endtime)) {
 985                        /* If we don't have a callback in flight, post one. */
 986                        if (!smp_load_acquire(&rbi.inflight)) {
 987                                /* RCU core before ->inflight = 1. */
 988                                smp_store_release(&rbi.inflight, 1);
 989                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 990                                /* Check if the boost test failed */
 991                                failed = failed ||
 992                                         rcu_torture_boost_failed(call_rcu_time,
 993                                                                 jiffies);
 994                                call_rcu_time = jiffies;
 995                        }
 996                        if (stutter_wait("rcu_torture_boost"))
 997                                sched_set_fifo_low(current);
 998                        if (torture_must_stop())
 999                                goto checkwait;
1000                }
1001
1002                /*
1003                 * If boost never happened, then inflight will always be 1, in
1004                 * this case the boost check would never happen in the above
1005                 * loop so do another one here.
1006                 */
1007                if (!failed && smp_load_acquire(&rbi.inflight))
1008                        rcu_torture_boost_failed(call_rcu_time, jiffies);
1009
1010                /*
1011                 * Set the start time of the next test interval.
1012                 * Yes, this is vulnerable to long delays, but such
1013                 * delays simply cause a false negative for the next
1014                 * interval.  Besides, we are running at RT priority,
1015                 * so delays should be relatively rare.
1016                 */
1017                while (oldstarttime == boost_starttime &&
1018                       !kthread_should_stop()) {
1019                        if (mutex_trylock(&boost_mutex)) {
1020                                boost_starttime = jiffies +
1021                                                  test_boost_interval * HZ;
1022                                mutex_unlock(&boost_mutex);
1023                                break;
1024                        }
1025                        schedule_timeout_uninterruptible(1);
1026                }
1027
1028                /* Go do the stutter. */
1029checkwait:      if (stutter_wait("rcu_torture_boost"))
1030                        sched_set_fifo_low(current);
1031        } while (!torture_must_stop());
1032
1033        /* Clean up and exit. */
1034        while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
1035                torture_shutdown_absorb("rcu_torture_boost");
1036                schedule_timeout_uninterruptible(1);
1037        }
1038        destroy_rcu_head_on_stack(&rbi.rcu);
1039        torture_kthread_stopping("rcu_torture_boost");
1040        return 0;
1041}
1042
1043/*
1044 * RCU torture force-quiescent-state kthread.  Repeatedly induces
1045 * bursts of calls to force_quiescent_state(), increasing the probability
1046 * of occurrence of some important types of race conditions.
1047 */
1048static int
1049rcu_torture_fqs(void *arg)
1050{
1051        unsigned long fqs_resume_time;
1052        int fqs_burst_remaining;
1053        int oldnice = task_nice(current);
1054
1055        VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
1056        do {
1057                fqs_resume_time = jiffies + fqs_stutter * HZ;
1058                while (time_before(jiffies, fqs_resume_time) &&
1059                       !kthread_should_stop()) {
1060                        schedule_timeout_interruptible(1);
1061                }
1062                fqs_burst_remaining = fqs_duration;
1063                while (fqs_burst_remaining > 0 &&
1064                       !kthread_should_stop()) {
1065                        cur_ops->fqs();
1066                        udelay(fqs_holdoff);
1067                        fqs_burst_remaining -= fqs_holdoff;
1068                }
1069                if (stutter_wait("rcu_torture_fqs"))
1070                        sched_set_normal(current, oldnice);
1071        } while (!torture_must_stop());
1072        torture_kthread_stopping("rcu_torture_fqs");
1073        return 0;
1074}
1075
1076// Used by writers to randomly choose from the available grace-period
1077// primitives.  The only purpose of the initialization is to size the array.
1078static int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC, RTWS_COND_GET, RTWS_POLL_GET, RTWS_SYNC };
1079static int nsynctypes;
1080
1081/*
1082 * Determine which grace-period primitives are available.
1083 */
1084static void rcu_torture_write_types(void)
1085{
1086        bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
1087        bool gp_poll1 = gp_poll, gp_sync1 = gp_sync;
1088
1089        /* Initialize synctype[] array.  If none set, take default. */
1090        if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_poll1 && !gp_sync1)
1091                gp_cond1 = gp_exp1 = gp_normal1 = gp_poll1 = gp_sync1 = true;
1092        if (gp_cond1 && cur_ops->get_gp_state && cur_ops->cond_sync) {
1093                synctype[nsynctypes++] = RTWS_COND_GET;
1094                pr_info("%s: Testing conditional GPs.\n", __func__);
1095        } else if (gp_cond && (!cur_ops->get_gp_state || !cur_ops->cond_sync)) {
1096                pr_alert("%s: gp_cond without primitives.\n", __func__);
1097        }
1098        if (gp_exp1 && cur_ops->exp_sync) {
1099                synctype[nsynctypes++] = RTWS_EXP_SYNC;
1100                pr_info("%s: Testing expedited GPs.\n", __func__);
1101        } else if (gp_exp && !cur_ops->exp_sync) {
1102                pr_alert("%s: gp_exp without primitives.\n", __func__);
1103        }
1104        if (gp_normal1 && cur_ops->deferred_free) {
1105                synctype[nsynctypes++] = RTWS_DEF_FREE;
1106                pr_info("%s: Testing asynchronous GPs.\n", __func__);
1107        } else if (gp_normal && !cur_ops->deferred_free) {
1108                pr_alert("%s: gp_normal without primitives.\n", __func__);
1109        }
1110        if (gp_poll1 && cur_ops->start_gp_poll && cur_ops->poll_gp_state) {
1111                synctype[nsynctypes++] = RTWS_POLL_GET;
1112                pr_info("%s: Testing polling GPs.\n", __func__);
1113        } else if (gp_poll && (!cur_ops->start_gp_poll || !cur_ops->poll_gp_state)) {
1114                pr_alert("%s: gp_poll without primitives.\n", __func__);
1115        }
1116        if (gp_sync1 && cur_ops->sync) {
1117                synctype[nsynctypes++] = RTWS_SYNC;
1118                pr_info("%s: Testing normal GPs.\n", __func__);
1119        } else if (gp_sync && !cur_ops->sync) {
1120                pr_alert("%s: gp_sync without primitives.\n", __func__);
1121        }
1122}
1123
1124/*
1125 * RCU torture writer kthread.  Repeatedly substitutes a new structure
1126 * for that pointed to by rcu_torture_current, freeing the old structure
1127 * after a series of grace periods (the "pipeline").
1128 */
1129static int
1130rcu_torture_writer(void *arg)
1131{
1132        bool boot_ended;
1133        bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
1134        unsigned long cookie;
1135        int expediting = 0;
1136        unsigned long gp_snap;
1137        int i;
1138        int idx;
1139        int oldnice = task_nice(current);
1140        struct rcu_torture *rp;
1141        struct rcu_torture *old_rp;
1142        static DEFINE_TORTURE_RANDOM(rand);
1143        bool stutter_waited;
1144
1145        VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
1146        if (!can_expedite)
1147                pr_alert("%s" TORTURE_FLAG
1148                         " GP expediting controlled from boot/sysfs for %s.\n",
1149                         torture_type, cur_ops->name);
1150        if (WARN_ONCE(nsynctypes == 0,
1151                      "rcu_torture_writer: No update-side primitives.\n")) {
1152                /*
1153                 * No updates primitives, so don't try updating.
1154                 * The resulting test won't be testing much, hence the
1155                 * above WARN_ONCE().
1156                 */
1157                rcu_torture_writer_state = RTWS_STOPPING;
1158                torture_kthread_stopping("rcu_torture_writer");
1159        }
1160
1161        do {
1162                rcu_torture_writer_state = RTWS_FIXED_DELAY;
1163                torture_hrtimeout_us(500, 1000, &rand);
1164                rp = rcu_torture_alloc();
1165                if (rp == NULL)
1166                        continue;
1167                rp->rtort_pipe_count = 0;
1168                rcu_torture_writer_state = RTWS_DELAY;
1169                udelay(torture_random(&rand) & 0x3ff);
1170                rcu_torture_writer_state = RTWS_REPLACE;
1171                old_rp = rcu_dereference_check(rcu_torture_current,
1172                                               current == writer_task);
1173                rp->rtort_mbtest = 1;
1174                rcu_assign_pointer(rcu_torture_current, rp);
1175                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1176                if (old_rp) {
1177                        i = old_rp->rtort_pipe_count;
1178                        if (i > RCU_TORTURE_PIPE_LEN)
1179                                i = RCU_TORTURE_PIPE_LEN;
1180                        atomic_inc(&rcu_torture_wcount[i]);
1181                        WRITE_ONCE(old_rp->rtort_pipe_count,
1182                                   old_rp->rtort_pipe_count + 1);
1183                        if (cur_ops->get_gp_state && cur_ops->poll_gp_state) {
1184                                idx = cur_ops->readlock();
1185                                cookie = cur_ops->get_gp_state();
1186                                WARN_ONCE(rcu_torture_writer_state != RTWS_DEF_FREE &&
1187                                          cur_ops->poll_gp_state(cookie),
1188                                          "%s: Cookie check 1 failed %s(%d) %lu->%lu\n",
1189                                          __func__,
1190                                          rcu_torture_writer_state_getname(),
1191                                          rcu_torture_writer_state,
1192                                          cookie, cur_ops->get_gp_state());
1193                                cur_ops->readunlock(idx);
1194                        }
1195                        switch (synctype[torture_random(&rand) % nsynctypes]) {
1196                        case RTWS_DEF_FREE:
1197                                rcu_torture_writer_state = RTWS_DEF_FREE;
1198                                cur_ops->deferred_free(old_rp);
1199                                break;
1200                        case RTWS_EXP_SYNC:
1201                                rcu_torture_writer_state = RTWS_EXP_SYNC;
1202                                cur_ops->exp_sync();
1203                                rcu_torture_pipe_update(old_rp);
1204                                break;
1205                        case RTWS_COND_GET:
1206                                rcu_torture_writer_state = RTWS_COND_GET;
1207                                gp_snap = cur_ops->get_gp_state();
1208                                torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1209                                rcu_torture_writer_state = RTWS_COND_SYNC;
1210                                cur_ops->cond_sync(gp_snap);
1211                                rcu_torture_pipe_update(old_rp);
1212                                break;
1213                        case RTWS_POLL_GET:
1214                                rcu_torture_writer_state = RTWS_POLL_GET;
1215                                gp_snap = cur_ops->start_gp_poll();
1216                                rcu_torture_writer_state = RTWS_POLL_WAIT;
1217                                while (!cur_ops->poll_gp_state(gp_snap))
1218                                        torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1219                                                                  &rand);
1220                                rcu_torture_pipe_update(old_rp);
1221                                break;
1222                        case RTWS_SYNC:
1223                                rcu_torture_writer_state = RTWS_SYNC;
1224                                cur_ops->sync();
1225                                rcu_torture_pipe_update(old_rp);
1226                                break;
1227                        default:
1228                                WARN_ON_ONCE(1);
1229                                break;
1230                        }
1231                        if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1232                                WARN_ONCE(rcu_torture_writer_state != RTWS_DEF_FREE &&
1233                                          !cur_ops->poll_gp_state(cookie),
1234                                          "%s: Cookie check 2 failed %s(%d) %lu->%lu\n",
1235                                          __func__,
1236                                          rcu_torture_writer_state_getname(),
1237                                          rcu_torture_writer_state,
1238                                          cookie, cur_ops->get_gp_state());
1239                }
1240                WRITE_ONCE(rcu_torture_current_version,
1241                           rcu_torture_current_version + 1);
1242                /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1243                if (can_expedite &&
1244                    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1245                        WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1246                        if (expediting >= 0)
1247                                rcu_expedite_gp();
1248                        else
1249                                rcu_unexpedite_gp();
1250                        if (++expediting > 3)
1251                                expediting = -expediting;
1252                } else if (!can_expedite) { /* Disabled during boot, recheck. */
1253                        can_expedite = !rcu_gp_is_expedited() &&
1254                                       !rcu_gp_is_normal();
1255                }
1256                rcu_torture_writer_state = RTWS_STUTTER;
1257                boot_ended = rcu_inkernel_boot_has_ended();
1258                stutter_waited = stutter_wait("rcu_torture_writer");
1259                if (stutter_waited &&
1260                    !READ_ONCE(rcu_fwd_cb_nodelay) &&
1261                    !cur_ops->slow_gps &&
1262                    !torture_must_stop() &&
1263                    boot_ended)
1264                        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1265                                if (list_empty(&rcu_tortures[i].rtort_free) &&
1266                                    rcu_access_pointer(rcu_torture_current) !=
1267                                    &rcu_tortures[i]) {
1268                                        rcu_ftrace_dump(DUMP_ALL);
1269                                        WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1270                                }
1271                if (stutter_waited)
1272                        sched_set_normal(current, oldnice);
1273        } while (!torture_must_stop());
1274        rcu_torture_current = NULL;  // Let stats task know that we are done.
1275        /* Reset expediting back to unexpedited. */
1276        if (expediting > 0)
1277                expediting = -expediting;
1278        while (can_expedite && expediting++ < 0)
1279                rcu_unexpedite_gp();
1280        WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1281        if (!can_expedite)
1282                pr_alert("%s" TORTURE_FLAG
1283                         " Dynamic grace-period expediting was disabled.\n",
1284                         torture_type);
1285        rcu_torture_writer_state = RTWS_STOPPING;
1286        torture_kthread_stopping("rcu_torture_writer");
1287        return 0;
1288}
1289
1290/*
1291 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1292 * delay between calls.
1293 */
1294static int
1295rcu_torture_fakewriter(void *arg)
1296{
1297        unsigned long gp_snap;
1298        DEFINE_TORTURE_RANDOM(rand);
1299
1300        VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1301        set_user_nice(current, MAX_NICE);
1302
1303        do {
1304                torture_hrtimeout_jiffies(torture_random(&rand) % 10, &rand);
1305                if (cur_ops->cb_barrier != NULL &&
1306                    torture_random(&rand) % (nfakewriters * 8) == 0) {
1307                        cur_ops->cb_barrier();
1308                } else {
1309                        switch (synctype[torture_random(&rand) % nsynctypes]) {
1310                        case RTWS_DEF_FREE:
1311                                break;
1312                        case RTWS_EXP_SYNC:
1313                                cur_ops->exp_sync();
1314                                break;
1315                        case RTWS_COND_GET:
1316                                gp_snap = cur_ops->get_gp_state();
1317                                torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand);
1318                                cur_ops->cond_sync(gp_snap);
1319                                break;
1320                        case RTWS_POLL_GET:
1321                                gp_snap = cur_ops->start_gp_poll();
1322                                while (!cur_ops->poll_gp_state(gp_snap)) {
1323                                        torture_hrtimeout_jiffies(torture_random(&rand) % 16,
1324                                                                  &rand);
1325                                }
1326                                break;
1327                        case RTWS_SYNC:
1328                                cur_ops->sync();
1329                                break;
1330                        default:
1331                                WARN_ON_ONCE(1);
1332                                break;
1333                        }
1334                }
1335                stutter_wait("rcu_torture_fakewriter");
1336        } while (!torture_must_stop());
1337
1338        torture_kthread_stopping("rcu_torture_fakewriter");
1339        return 0;
1340}
1341
1342static void rcu_torture_timer_cb(struct rcu_head *rhp)
1343{
1344        kfree(rhp);
1345}
1346
1347// Set up and carry out testing of RCU's global memory ordering
1348static void rcu_torture_reader_do_mbchk(long myid, struct rcu_torture *rtp,
1349                                        struct torture_random_state *trsp)
1350{
1351        unsigned long loops;
1352        int noc = torture_num_online_cpus();
1353        int rdrchked;
1354        int rdrchker;
1355        struct rcu_torture_reader_check *rtrcp; // Me.
1356        struct rcu_torture_reader_check *rtrcp_assigner; // Assigned us to do checking.
1357        struct rcu_torture_reader_check *rtrcp_chked; // Reader being checked.
1358        struct rcu_torture_reader_check *rtrcp_chker; // Reader doing checking when not me.
1359
1360        if (myid < 0)
1361                return; // Don't try this from timer handlers.
1362
1363        // Increment my counter.
1364        rtrcp = &rcu_torture_reader_mbchk[myid];
1365        WRITE_ONCE(rtrcp->rtc_myloops, rtrcp->rtc_myloops + 1);
1366
1367        // Attempt to assign someone else some checking work.
1368        rdrchked = torture_random(trsp) % nrealreaders;
1369        rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1370        rdrchker = torture_random(trsp) % nrealreaders;
1371        rtrcp_chker = &rcu_torture_reader_mbchk[rdrchker];
1372        if (rdrchked != myid && rdrchked != rdrchker && noc >= rdrchked && noc >= rdrchker &&
1373            smp_load_acquire(&rtrcp->rtc_chkrdr) < 0 && // Pairs with smp_store_release below.
1374            !READ_ONCE(rtp->rtort_chkp) &&
1375            !smp_load_acquire(&rtrcp_chker->rtc_assigner)) { // Pairs with smp_store_release below.
1376                rtrcp->rtc_chkloops = READ_ONCE(rtrcp_chked->rtc_myloops);
1377                WARN_ON_ONCE(rtrcp->rtc_chkrdr >= 0);
1378                rtrcp->rtc_chkrdr = rdrchked;
1379                WARN_ON_ONCE(rtrcp->rtc_ready); // This gets set after the grace period ends.
1380                if (cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, NULL, rtrcp) ||
1381                    cmpxchg_relaxed(&rtp->rtort_chkp, NULL, rtrcp))
1382                        (void)cmpxchg_relaxed(&rtrcp_chker->rtc_assigner, rtrcp, NULL); // Back out.
1383        }
1384
1385        // If assigned some completed work, do it!
1386        rtrcp_assigner = READ_ONCE(rtrcp->rtc_assigner);
1387        if (!rtrcp_assigner || !smp_load_acquire(&rtrcp_assigner->rtc_ready))
1388                return; // No work or work not yet ready.
1389        rdrchked = rtrcp_assigner->rtc_chkrdr;
1390        if (WARN_ON_ONCE(rdrchked < 0))
1391                return;
1392        rtrcp_chked = &rcu_torture_reader_mbchk[rdrchked];
1393        loops = READ_ONCE(rtrcp_chked->rtc_myloops);
1394        atomic_inc(&n_rcu_torture_mbchk_tries);
1395        if (ULONG_CMP_LT(loops, rtrcp_assigner->rtc_chkloops))
1396                atomic_inc(&n_rcu_torture_mbchk_fail);
1397        rtrcp_assigner->rtc_chkloops = loops + ULONG_MAX / 2;
1398        rtrcp_assigner->rtc_ready = 0;
1399        smp_store_release(&rtrcp->rtc_assigner, NULL); // Someone else can assign us work.
1400        smp_store_release(&rtrcp_assigner->rtc_chkrdr, -1); // Assigner can again assign.
1401}
1402
1403/*
1404 * Do one extension of an RCU read-side critical section using the
1405 * current reader state in readstate (set to zero for initial entry
1406 * to extended critical section), set the new state as specified by
1407 * newstate (set to zero for final exit from extended critical section),
1408 * and random-number-generator state in trsp.  If this is neither the
1409 * beginning or end of the critical section and if there was actually a
1410 * change, do a ->read_delay().
1411 */
1412static void rcutorture_one_extend(int *readstate, int newstate,
1413                                  struct torture_random_state *trsp,
1414                                  struct rt_read_seg *rtrsp)
1415{
1416        unsigned long flags;
1417        int idxnew = -1;
1418        int idxold = *readstate;
1419        int statesnew = ~*readstate & newstate;
1420        int statesold = *readstate & ~newstate;
1421
1422        WARN_ON_ONCE(idxold < 0);
1423        WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1424        rtrsp->rt_readstate = newstate;
1425
1426        /* First, put new protection in place to avoid critical-section gap. */
1427        if (statesnew & RCUTORTURE_RDR_BH)
1428                local_bh_disable();
1429        if (statesnew & RCUTORTURE_RDR_IRQ)
1430                local_irq_disable();
1431        if (statesnew & RCUTORTURE_RDR_PREEMPT)
1432                preempt_disable();
1433        if (statesnew & RCUTORTURE_RDR_RBH)
1434                rcu_read_lock_bh();
1435        if (statesnew & RCUTORTURE_RDR_SCHED)
1436                rcu_read_lock_sched();
1437        if (statesnew & RCUTORTURE_RDR_RCU)
1438                idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1439
1440        /* Next, remove old protection, irq first due to bh conflict. */
1441        if (statesold & RCUTORTURE_RDR_IRQ)
1442                local_irq_enable();
1443        if (statesold & RCUTORTURE_RDR_BH)
1444                local_bh_enable();
1445        if (statesold & RCUTORTURE_RDR_PREEMPT)
1446                preempt_enable();
1447        if (statesold & RCUTORTURE_RDR_RBH)
1448                rcu_read_unlock_bh();
1449        if (statesold & RCUTORTURE_RDR_SCHED)
1450                rcu_read_unlock_sched();
1451        if (statesold & RCUTORTURE_RDR_RCU) {
1452                bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);
1453
1454                if (lockit)
1455                        raw_spin_lock_irqsave(&current->pi_lock, flags);
1456                cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1457                if (lockit)
1458                        raw_spin_unlock_irqrestore(&current->pi_lock, flags);
1459        }
1460
1461        /* Delay if neither beginning nor end and there was a change. */
1462        if ((statesnew || statesold) && *readstate && newstate)
1463                cur_ops->read_delay(trsp, rtrsp);
1464
1465        /* Update the reader state. */
1466        if (idxnew == -1)
1467                idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1468        WARN_ON_ONCE(idxnew < 0);
1469        WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1470        *readstate = idxnew | newstate;
1471        WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1472        WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1473}
1474
1475/* Return the biggest extendables mask given current RCU and boot parameters. */
1476static int rcutorture_extend_mask_max(void)
1477{
1478        int mask;
1479
1480        WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1481        mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1482        mask = mask | RCUTORTURE_RDR_RCU;
1483        return mask;
1484}
1485
1486/* Return a random protection state mask, but with at least one bit set. */
1487static int
1488rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1489{
1490        int mask = rcutorture_extend_mask_max();
1491        unsigned long randmask1 = torture_random(trsp) >> 8;
1492        unsigned long randmask2 = randmask1 >> 3;
1493
1494        WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1495        /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1496        if (!(randmask1 & 0x7))
1497                mask = mask & randmask2;
1498        else
1499                mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1500        /* Can't enable bh w/irq disabled. */
1501        if ((mask & RCUTORTURE_RDR_IRQ) &&
1502            ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1503             (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1504                mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1505        return mask ?: RCUTORTURE_RDR_RCU;
1506}
1507
1508/*
1509 * Do a randomly selected number of extensions of an existing RCU read-side
1510 * critical section.
1511 */
1512static struct rt_read_seg *
1513rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1514                       struct rt_read_seg *rtrsp)
1515{
1516        int i;
1517        int j;
1518        int mask = rcutorture_extend_mask_max();
1519
1520        WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1521        if (!((mask - 1) & mask))
1522                return rtrsp;  /* Current RCU reader not extendable. */
1523        /* Bias towards larger numbers of loops. */
1524        i = (torture_random(trsp) >> 3);
1525        i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1526        for (j = 0; j < i; j++) {
1527                mask = rcutorture_extend_mask(*readstate, trsp);
1528                rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1529        }
1530        return &rtrsp[j];
1531}
1532
1533/*
1534 * Do one read-side critical section, returning false if there was
1535 * no data to read.  Can be invoked both from process context and
1536 * from a timer handler.
1537 */
1538static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
1539{
1540        unsigned long cookie;
1541        int i;
1542        unsigned long started;
1543        unsigned long completed;
1544        int newstate;
1545        struct rcu_torture *p;
1546        int pipe_count;
1547        int readstate = 0;
1548        struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1549        struct rt_read_seg *rtrsp = &rtseg[0];
1550        struct rt_read_seg *rtrsp1;
1551        unsigned long long ts;
1552
1553        WARN_ON_ONCE(!rcu_is_watching());
1554        newstate = rcutorture_extend_mask(readstate, trsp);
1555        rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1556        if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1557                cookie = cur_ops->get_gp_state();
1558        started = cur_ops->get_gp_seq();
1559        ts = rcu_trace_clock_local();
1560        p = rcu_dereference_check(rcu_torture_current,
1561                                  rcu_read_lock_bh_held() ||
1562                                  rcu_read_lock_sched_held() ||
1563                                  srcu_read_lock_held(srcu_ctlp) ||
1564                                  rcu_read_lock_trace_held() ||
1565                                  torturing_tasks());
1566        if (p == NULL) {
1567                /* Wait for rcu_torture_writer to get underway */
1568                rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1569                return false;
1570        }
1571        if (p->rtort_mbtest == 0)
1572                atomic_inc(&n_rcu_torture_mberror);
1573        rcu_torture_reader_do_mbchk(myid, p, trsp);
1574        rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1575        preempt_disable();
1576        pipe_count = READ_ONCE(p->rtort_pipe_count);
1577        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1578                /* Should not happen, but... */
1579                pipe_count = RCU_TORTURE_PIPE_LEN;
1580        }
1581        completed = cur_ops->get_gp_seq();
1582        if (pipe_count > 1) {
1583                do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1584                                          ts, started, completed);
1585                rcu_ftrace_dump(DUMP_ALL);
1586        }
1587        __this_cpu_inc(rcu_torture_count[pipe_count]);
1588        completed = rcutorture_seq_diff(completed, started);
1589        if (completed > RCU_TORTURE_PIPE_LEN) {
1590                /* Should not happen, but... */
1591                completed = RCU_TORTURE_PIPE_LEN;
1592        }
1593        __this_cpu_inc(rcu_torture_batch[completed]);
1594        preempt_enable();
1595        if (cur_ops->get_gp_state && cur_ops->poll_gp_state)
1596                WARN_ONCE(cur_ops->poll_gp_state(cookie),
1597                          "%s: Cookie check 3 failed %s(%d) %lu->%lu\n",
1598                          __func__,
1599                          rcu_torture_writer_state_getname(),
1600                          rcu_torture_writer_state,
1601                          cookie, cur_ops->get_gp_state());
1602        rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1603        WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1604        // This next splat is expected behavior if leakpointer, especially
1605        // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
1606        WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);
1607
1608        /* If error or close call, record the sequence of reader protections. */
1609        if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1610                i = 0;
1611                for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1612                        err_segs[i++] = *rtrsp1;
1613                rt_read_nsegs = i;
1614        }
1615
1616        return true;
1617}
1618
1619static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1620
1621/*
1622 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1623 * incrementing the corresponding element of the pipeline array.  The
1624 * counter in the element should never be greater than 1, otherwise, the
1625 * RCU implementation is broken.
1626 */
1627static void rcu_torture_timer(struct timer_list *unused)
1628{
1629        atomic_long_inc(&n_rcu_torture_timers);
1630        (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand), -1);
1631
1632        /* Test call_rcu() invocation from interrupt handler. */
1633        if (cur_ops->call) {
1634                struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1635
1636                if (rhp)
1637                        cur_ops->call(rhp, rcu_torture_timer_cb);
1638        }
1639}
1640
1641/*
1642 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1643 * incrementing the corresponding element of the pipeline array.  The
1644 * counter in the element should never be greater than 1, otherwise, the
1645 * RCU implementation is broken.
1646 */
1647static int
1648rcu_torture_reader(void *arg)
1649{
1650        unsigned long lastsleep = jiffies;
1651        long myid = (long)arg;
1652        int mynumonline = myid;
1653        DEFINE_TORTURE_RANDOM(rand);
1654        struct timer_list t;
1655
1656        VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1657        set_user_nice(current, MAX_NICE);
1658        if (irqreader && cur_ops->irq_capable)
1659                timer_setup_on_stack(&t, rcu_torture_timer, 0);
1660        tick_dep_set_task(current, TICK_DEP_BIT_RCU);
1661        do {
1662                if (irqreader && cur_ops->irq_capable) {
1663                        if (!timer_pending(&t))
1664                                mod_timer(&t, jiffies + 1);
1665                }
1666                if (!rcu_torture_one_read(&rand, myid) && !torture_must_stop())
1667                        schedule_timeout_interruptible(HZ);
1668                if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
1669                        torture_hrtimeout_us(500, 1000, &rand);
1670                        lastsleep = jiffies + 10;
1671                }
1672                while (torture_num_online_cpus() < mynumonline && !torture_must_stop())
1673                        schedule_timeout_interruptible(HZ / 5);
1674                stutter_wait("rcu_torture_reader");
1675        } while (!torture_must_stop());
1676        if (irqreader && cur_ops->irq_capable) {
1677                del_timer_sync(&t);
1678                destroy_timer_on_stack(&t);
1679        }
1680        tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
1681        torture_kthread_stopping("rcu_torture_reader");
1682        return 0;
1683}
1684
1685/*
1686 * Randomly Toggle CPUs' callback-offload state.  This uses hrtimers to
1687 * increase race probabilities and fuzzes the interval between toggling.
1688 */
1689static int rcu_nocb_toggle(void *arg)
1690{
1691        int cpu;
1692        int maxcpu = -1;
1693        int oldnice = task_nice(current);
1694        long r;
1695        DEFINE_TORTURE_RANDOM(rand);
1696        ktime_t toggle_delay;
1697        unsigned long toggle_fuzz;
1698        ktime_t toggle_interval = ms_to_ktime(nocbs_toggle);
1699
1700        VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started");
1701        while (!rcu_inkernel_boot_has_ended())
1702                schedule_timeout_interruptible(HZ / 10);
1703        for_each_online_cpu(cpu)
1704                maxcpu = cpu;
1705        WARN_ON(maxcpu < 0);
1706        if (toggle_interval > ULONG_MAX)
1707                toggle_fuzz = ULONG_MAX >> 3;
1708        else
1709                toggle_fuzz = toggle_interval >> 3;
1710        if (toggle_fuzz <= 0)
1711                toggle_fuzz = NSEC_PER_USEC;
1712        do {
1713                r = torture_random(&rand);
1714                cpu = (r >> 4) % (maxcpu + 1);
1715                if (r & 0x1) {
1716                        rcu_nocb_cpu_offload(cpu);
1717                        atomic_long_inc(&n_nocb_offload);
1718                } else {
1719                        rcu_nocb_cpu_deoffload(cpu);
1720                        atomic_long_inc(&n_nocb_deoffload);
1721                }
1722                toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
1723                set_current_state(TASK_INTERRUPTIBLE);
1724                schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
1725                if (stutter_wait("rcu_nocb_toggle"))
1726                        sched_set_normal(current, oldnice);
1727        } while (!torture_must_stop());
1728        torture_kthread_stopping("rcu_nocb_toggle");
1729        return 0;
1730}
1731
1732/*
1733 * Print torture statistics.  Caller must ensure that there is only
1734 * one call to this function at a given time!!!  This is normally
1735 * accomplished by relying on the module system to only have one copy
1736 * of the module loaded, and then by giving the rcu_torture_stats
1737 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1738 * thread is not running).
1739 */
1740static void
1741rcu_torture_stats_print(void)
1742{
1743        int cpu;
1744        int i;
1745        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1746        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1747        struct rcu_torture *rtcp;
1748        static unsigned long rtcv_snap = ULONG_MAX;
1749        static bool splatted;
1750        struct task_struct *wtp;
1751
1752        for_each_possible_cpu(cpu) {
1753                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1754                        pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
1755                        batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
1756                }
1757        }
1758        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1759                if (pipesummary[i] != 0)
1760                        break;
1761        }
1762
1763        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1764        rtcp = rcu_access_pointer(rcu_torture_current);
1765        pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1766                rtcp,
1767                rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
1768                rcu_torture_current_version,
1769                list_empty(&rcu_torture_freelist),
1770                atomic_read(&n_rcu_torture_alloc),
1771                atomic_read(&n_rcu_torture_alloc_fail),
1772                atomic_read(&n_rcu_torture_free));
1773        pr_cont("rtmbe: %d rtmbkf: %d/%d rtbe: %ld rtbke: %ld rtbre: %ld ",
1774                atomic_read(&n_rcu_torture_mberror),
1775                atomic_read(&n_rcu_torture_mbchk_fail), atomic_read(&n_rcu_torture_mbchk_tries),
1776                n_rcu_torture_barrier_error,
1777                n_rcu_torture_boost_ktrerror,
1778                n_rcu_torture_boost_rterror);
1779        pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1780                n_rcu_torture_boost_failure,
1781                n_rcu_torture_boosts,
1782                atomic_long_read(&n_rcu_torture_timers));
1783        torture_onoff_stats();
1784        pr_cont("barrier: %ld/%ld:%ld ",
1785                data_race(n_barrier_successes),
1786                data_race(n_barrier_attempts),
1787                data_race(n_rcu_torture_barrier_error));
1788        pr_cont("read-exits: %ld ", data_race(n_read_exits)); // Statistic.
1789        pr_cont("nocb-toggles: %ld:%ld\n",
1790                atomic_long_read(&n_nocb_offload), atomic_long_read(&n_nocb_deoffload));
1791
1792        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1793        if (atomic_read(&n_rcu_torture_mberror) ||
1794            atomic_read(&n_rcu_torture_mbchk_fail) ||
1795            n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
1796            n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
1797            i > 1) {
1798                pr_cont("%s", "!!! ");
1799                atomic_inc(&n_rcu_torture_error);
1800                WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
1801                WARN_ON_ONCE(atomic_read(&n_rcu_torture_mbchk_fail));
1802                WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
1803                WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
1804                WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
1805                WARN_ON_ONCE(n_rcu_torture_boost_failure); // RCU boost failed
1806                WARN_ON_ONCE(i > 1); // Too-short grace period
1807        }
1808        pr_cont("Reader Pipe: ");
1809        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1810                pr_cont(" %ld", pipesummary[i]);
1811        pr_cont("\n");
1812
1813        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1814        pr_cont("Reader Batch: ");
1815        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1816                pr_cont(" %ld", batchsummary[i]);
1817        pr_cont("\n");
1818
1819        pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1820        pr_cont("Free-Block Circulation: ");
1821        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1822                pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1823        }
1824        pr_cont("\n");
1825
1826        if (cur_ops->stats)
1827                cur_ops->stats();
1828        if (rtcv_snap == rcu_torture_current_version &&
1829            rcu_access_pointer(rcu_torture_current) &&
1830            !rcu_stall_is_suppressed()) {
1831                int __maybe_unused flags = 0;
1832                unsigned long __maybe_unused gp_seq = 0;
1833
1834                rcutorture_get_gp_data(cur_ops->ttype,
1835                                       &flags, &gp_seq);
1836                srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1837                                        &flags, &gp_seq);
1838                wtp = READ_ONCE(writer_task);
1839                pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#x cpu %d\n",
1840                         rcu_torture_writer_state_getname(),
1841                         rcu_torture_writer_state, gp_seq, flags,
1842                         wtp == NULL ? ~0U : wtp->__state,
1843                         wtp == NULL ? -1 : (int)task_cpu(wtp));
1844                if (!splatted && wtp) {
1845                        sched_show_task(wtp);
1846                        splatted = true;
1847                }
1848                if (cur_ops->gp_kthread_dbg)
1849                        cur_ops->gp_kthread_dbg();
1850                rcu_ftrace_dump(DUMP_ALL);
1851        }
1852        rtcv_snap = rcu_torture_current_version;
1853}
1854
1855/*
1856 * Periodically prints torture statistics, if periodic statistics printing
1857 * was specified via the stat_interval module parameter.
1858 */
1859static int
1860rcu_torture_stats(void *arg)
1861{
1862        VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1863        do {
1864                schedule_timeout_interruptible(stat_interval * HZ);
1865                rcu_torture_stats_print();
1866                torture_shutdown_absorb("rcu_torture_stats");
1867        } while (!torture_must_stop());
1868        torture_kthread_stopping("rcu_torture_stats");
1869        return 0;
1870}
1871
1872static void
1873rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1874{
1875        pr_alert("%s" TORTURE_FLAG
1876                 "--- %s: nreaders=%d nfakewriters=%d "
1877                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1878                 "shuffle_interval=%d stutter=%d irqreader=%d "
1879                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1880                 "test_boost=%d/%d test_boost_interval=%d "
1881                 "test_boost_duration=%d shutdown_secs=%d "
1882                 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1883                 "stall_cpu_block=%d "
1884                 "n_barrier_cbs=%d "
1885                 "onoff_interval=%d onoff_holdoff=%d "
1886                 "read_exit_delay=%d read_exit_burst=%d "
1887                 "nocbs_nthreads=%d nocbs_toggle=%d\n",
1888                 torture_type, tag, nrealreaders, nfakewriters,
1889                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1890                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1891                 test_boost, cur_ops->can_boost,
1892                 test_boost_interval, test_boost_duration, shutdown_secs,
1893                 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1894                 stall_cpu_block,
1895                 n_barrier_cbs,
1896                 onoff_interval, onoff_holdoff,
1897                 read_exit_delay, read_exit_burst,
1898                 nocbs_nthreads, nocbs_toggle);
1899}
1900
1901static int rcutorture_booster_cleanup(unsigned int cpu)
1902{
1903        struct task_struct *t;
1904
1905        if (boost_tasks[cpu] == NULL)
1906                return 0;
1907        mutex_lock(&boost_mutex);
1908        t = boost_tasks[cpu];
1909        boost_tasks[cpu] = NULL;
1910        rcu_torture_enable_rt_throttle();
1911        mutex_unlock(&boost_mutex);
1912
1913        /* This must be outside of the mutex, otherwise deadlock! */
1914        torture_stop_kthread(rcu_torture_boost, t);
1915        return 0;
1916}
1917
1918static int rcutorture_booster_init(unsigned int cpu)
1919{
1920        int retval;
1921
1922        if (boost_tasks[cpu] != NULL)
1923                return 0;  /* Already created, nothing more to do. */
1924
1925        /* Don't allow time recalculation while creating a new task. */
1926        mutex_lock(&boost_mutex);
1927        rcu_torture_disable_rt_throttle();
1928        VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1929        boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1930                                                  cpu_to_node(cpu),
1931                                                  "rcu_torture_boost");
1932        if (IS_ERR(boost_tasks[cpu])) {
1933                retval = PTR_ERR(boost_tasks[cpu]);
1934                VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1935                n_rcu_torture_boost_ktrerror++;
1936                boost_tasks[cpu] = NULL;
1937                mutex_unlock(&boost_mutex);
1938                return retval;
1939        }
1940        kthread_bind(boost_tasks[cpu], cpu);
1941        wake_up_process(boost_tasks[cpu]);
1942        mutex_unlock(&boost_mutex);
1943        return 0;
1944}
1945
1946/*
1947 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1948 * induces a CPU stall for the time specified by stall_cpu.
1949 */
1950static int rcu_torture_stall(void *args)
1951{
1952        int idx;
1953        unsigned long stop_at;
1954
1955        VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1956        if (stall_cpu_holdoff > 0) {
1957                VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1958                schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1959                VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1960        }
1961        if (!kthread_should_stop() && stall_gp_kthread > 0) {
1962                VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
1963                rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
1964                for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
1965                        if (kthread_should_stop())
1966                                break;
1967                        schedule_timeout_uninterruptible(HZ);
1968                }
1969        }
1970        if (!kthread_should_stop() && stall_cpu > 0) {
1971                VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
1972                stop_at = ktime_get_seconds() + stall_cpu;
1973                /* RCU CPU stall is expected behavior in following code. */
1974                idx = cur_ops->readlock();
1975                if (stall_cpu_irqsoff)
1976                        local_irq_disable();
1977                else if (!stall_cpu_block)
1978                        preempt_disable();
1979                pr_alert("rcu_torture_stall start on CPU %d.\n",
1980                         raw_smp_processor_id());
1981                while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1982                                    stop_at))
1983                        if (stall_cpu_block)
1984                                schedule_timeout_uninterruptible(HZ);
1985                if (stall_cpu_irqsoff)
1986                        local_irq_enable();
1987                else if (!stall_cpu_block)
1988                        preempt_enable();
1989                cur_ops->readunlock(idx);
1990        }
1991        pr_alert("rcu_torture_stall end.\n");
1992        torture_shutdown_absorb("rcu_torture_stall");
1993        while (!kthread_should_stop())
1994                schedule_timeout_interruptible(10 * HZ);
1995        return 0;
1996}
1997
1998/* Spawn CPU-stall kthread, if stall_cpu specified. */
1999static int __init rcu_torture_stall_init(void)
2000{
2001        if (stall_cpu <= 0 && stall_gp_kthread <= 0)
2002                return 0;
2003        return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
2004}
2005
2006/* State structure for forward-progress self-propagating RCU callback. */
2007struct fwd_cb_state {
2008        struct rcu_head rh;
2009        int stop;
2010};
2011
2012/*
2013 * Forward-progress self-propagating RCU callback function.  Because
2014 * callbacks run from softirq, this function is an implicit RCU read-side
2015 * critical section.
2016 */
2017static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
2018{
2019        struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
2020
2021        if (READ_ONCE(fcsp->stop)) {
2022                WRITE_ONCE(fcsp->stop, 2);
2023                return;
2024        }
2025        cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
2026}
2027
2028/* State for continuous-flood RCU callbacks. */
2029struct rcu_fwd_cb {
2030        struct rcu_head rh;
2031        struct rcu_fwd_cb *rfc_next;
2032        struct rcu_fwd *rfc_rfp;
2033        int rfc_gps;
2034};
2035
2036#define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
2037#define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
2038#define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
2039#define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
2040#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
2041
2042struct rcu_launder_hist {
2043        long n_launders;
2044        unsigned long launder_gp_seq;
2045};
2046
2047struct rcu_fwd {
2048        spinlock_t rcu_fwd_lock;
2049        struct rcu_fwd_cb *rcu_fwd_cb_head;
2050        struct rcu_fwd_cb **rcu_fwd_cb_tail;
2051        long n_launders_cb;
2052        unsigned long rcu_fwd_startat;
2053        struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
2054        unsigned long rcu_launder_gp_seq_start;
2055};
2056
2057static DEFINE_MUTEX(rcu_fwd_mutex);
2058static struct rcu_fwd *rcu_fwds;
2059static bool rcu_fwd_emergency_stop;
2060
2061static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
2062{
2063        unsigned long gps;
2064        unsigned long gps_old;
2065        int i;
2066        int j;
2067
2068        for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
2069                if (rfp->n_launders_hist[i].n_launders > 0)
2070                        break;
2071        pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
2072                 __func__, jiffies - rfp->rcu_fwd_startat);
2073        gps_old = rfp->rcu_launder_gp_seq_start;
2074        for (j = 0; j <= i; j++) {
2075                gps = rfp->n_launders_hist[j].launder_gp_seq;
2076                pr_cont(" %ds/%d: %ld:%ld",
2077                        j + 1, FWD_CBS_HIST_DIV,
2078                        rfp->n_launders_hist[j].n_launders,
2079                        rcutorture_seq_diff(gps, gps_old));
2080                gps_old = gps;
2081        }
2082        pr_cont("\n");
2083}
2084
2085/* Callback function for continuous-flood RCU callbacks. */
2086static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
2087{
2088        unsigned long flags;
2089        int i;
2090        struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
2091        struct rcu_fwd_cb **rfcpp;
2092        struct rcu_fwd *rfp = rfcp->rfc_rfp;
2093
2094        rfcp->rfc_next = NULL;
2095        rfcp->rfc_gps++;
2096        spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2097        rfcpp = rfp->rcu_fwd_cb_tail;
2098        rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
2099        WRITE_ONCE(*rfcpp, rfcp);
2100        WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
2101        i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
2102        if (i >= ARRAY_SIZE(rfp->n_launders_hist))
2103                i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
2104        rfp->n_launders_hist[i].n_launders++;
2105        rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
2106        spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2107}
2108
2109// Give the scheduler a chance, even on nohz_full CPUs.
2110static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
2111{
2112        if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
2113                // Real call_rcu() floods hit userspace, so emulate that.
2114                if (need_resched() || (iter & 0xfff))
2115                        schedule();
2116                return;
2117        }
2118        // No userspace emulation: CB invocation throttles call_rcu()
2119        cond_resched();
2120}
2121
2122/*
2123 * Free all callbacks on the rcu_fwd_cb_head list, either because the
2124 * test is over or because we hit an OOM event.
2125 */
2126static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
2127{
2128        unsigned long flags;
2129        unsigned long freed = 0;
2130        struct rcu_fwd_cb *rfcp;
2131
2132        for (;;) {
2133                spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
2134                rfcp = rfp->rcu_fwd_cb_head;
2135                if (!rfcp) {
2136                        spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2137                        break;
2138                }
2139                rfp->rcu_fwd_cb_head = rfcp->rfc_next;
2140                if (!rfp->rcu_fwd_cb_head)
2141                        rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2142                spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
2143                kfree(rfcp);
2144                freed++;
2145                rcu_torture_fwd_prog_cond_resched(freed);
2146                if (tick_nohz_full_enabled()) {
2147                        local_irq_save(flags);
2148                        rcu_momentary_dyntick_idle();
2149                        local_irq_restore(flags);
2150                }
2151        }
2152        return freed;
2153}
2154
2155/* Carry out need_resched()/cond_resched() forward-progress testing. */
2156static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
2157                                    int *tested, int *tested_tries)
2158{
2159        unsigned long cver;
2160        unsigned long dur;
2161        struct fwd_cb_state fcs;
2162        unsigned long gps;
2163        int idx;
2164        int sd;
2165        int sd4;
2166        bool selfpropcb = false;
2167        unsigned long stopat;
2168        static DEFINE_TORTURE_RANDOM(trs);
2169
2170        if (!cur_ops->sync)
2171                return; // Cannot do need_resched() forward progress testing without ->sync.
2172        if (cur_ops->call && cur_ops->cb_barrier) {
2173                init_rcu_head_on_stack(&fcs.rh);
2174                selfpropcb = true;
2175        }
2176
2177        /* Tight loop containing cond_resched(). */
2178        WRITE_ONCE(rcu_fwd_cb_nodelay, true);
2179        cur_ops->sync(); /* Later readers see above write. */
2180        if  (selfpropcb) {
2181                WRITE_ONCE(fcs.stop, 0);
2182                cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
2183        }
2184        cver = READ_ONCE(rcu_torture_current_version);
2185        gps = cur_ops->get_gp_seq();
2186        sd = cur_ops->stall_dur() + 1;
2187        sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
2188        dur = sd4 + torture_random(&trs) % (sd - sd4);
2189        WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2190        stopat = rfp->rcu_fwd_startat + dur;
2191        while (time_before(jiffies, stopat) &&
2192               !shutdown_time_arrived() &&
2193               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2194                idx = cur_ops->readlock();
2195                udelay(10);
2196                cur_ops->readunlock(idx);
2197                if (!fwd_progress_need_resched || need_resched())
2198                        cond_resched();
2199        }
2200        (*tested_tries)++;
2201        if (!time_before(jiffies, stopat) &&
2202            !shutdown_time_arrived() &&
2203            !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2204                (*tested)++;
2205                cver = READ_ONCE(rcu_torture_current_version) - cver;
2206                gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2207                WARN_ON(!cver && gps < 2);
2208                pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
2209        }
2210        if (selfpropcb) {
2211                WRITE_ONCE(fcs.stop, 1);
2212                cur_ops->sync(); /* Wait for running CB to complete. */
2213                cur_ops->cb_barrier(); /* Wait for queued callbacks. */
2214        }
2215
2216        if (selfpropcb) {
2217                WARN_ON(READ_ONCE(fcs.stop) != 2);
2218                destroy_rcu_head_on_stack(&fcs.rh);
2219        }
2220        schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
2221        WRITE_ONCE(rcu_fwd_cb_nodelay, false);
2222}
2223
2224/* Carry out call_rcu() forward-progress testing. */
2225static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
2226{
2227        unsigned long cver;
2228        unsigned long flags;
2229        unsigned long gps;
2230        int i;
2231        long n_launders;
2232        long n_launders_cb_snap;
2233        long n_launders_sa;
2234        long n_max_cbs;
2235        long n_max_gps;
2236        struct rcu_fwd_cb *rfcp;
2237        struct rcu_fwd_cb *rfcpn;
2238        unsigned long stopat;
2239        unsigned long stoppedat;
2240
2241        if (READ_ONCE(rcu_fwd_emergency_stop))
2242                return; /* Get out of the way quickly, no GP wait! */
2243        if (!cur_ops->call)
2244                return; /* Can't do call_rcu() fwd prog without ->call. */
2245
2246        /* Loop continuously posting RCU callbacks. */
2247        WRITE_ONCE(rcu_fwd_cb_nodelay, true);
2248        cur_ops->sync(); /* Later readers see above write. */
2249        WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
2250        stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
2251        n_launders = 0;
2252        rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
2253        n_launders_sa = 0;
2254        n_max_cbs = 0;
2255        n_max_gps = 0;
2256        for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
2257                rfp->n_launders_hist[i].n_launders = 0;
2258        cver = READ_ONCE(rcu_torture_current_version);
2259        gps = cur_ops->get_gp_seq();
2260        rfp->rcu_launder_gp_seq_start = gps;
2261        tick_dep_set_task(current, TICK_DEP_BIT_RCU);
2262        while (time_before(jiffies, stopat) &&
2263               !shutdown_time_arrived() &&
2264               !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2265                rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
2266                rfcpn = NULL;
2267                if (rfcp)
2268                        rfcpn = READ_ONCE(rfcp->rfc_next);
2269                if (rfcpn) {
2270                        if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
2271                            ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
2272                                break;
2273                        rfp->rcu_fwd_cb_head = rfcpn;
2274                        n_launders++;
2275                        n_launders_sa++;
2276                } else {
2277                        rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
2278                        if (WARN_ON_ONCE(!rfcp)) {
2279                                schedule_timeout_interruptible(1);
2280                                continue;
2281                        }
2282                        n_max_cbs++;
2283                        n_launders_sa = 0;
2284                        rfcp->rfc_gps = 0;
2285                        rfcp->rfc_rfp = rfp;
2286                }
2287                cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
2288                rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
2289                if (tick_nohz_full_enabled()) {
2290                        local_irq_save(flags);
2291                        rcu_momentary_dyntick_idle();
2292                        local_irq_restore(flags);
2293                }
2294        }
2295        stoppedat = jiffies;
2296        n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
2297        cver = READ_ONCE(rcu_torture_current_version) - cver;
2298        gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2299        cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
2300        (void)rcu_torture_fwd_prog_cbfree(rfp);
2301
2302        if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
2303            !shutdown_time_arrived()) {
2304                WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
2305                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",
2306                         __func__,
2307                         stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
2308                         n_launders + n_max_cbs - n_launders_cb_snap,
2309                         n_launders, n_launders_sa,
2310                         n_max_gps, n_max_cbs, cver, gps);
2311                rcu_torture_fwd_cb_hist(rfp);
2312        }
2313        schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
2314        tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
2315        WRITE_ONCE(rcu_fwd_cb_nodelay, false);
2316}
2317
2318
2319/*
2320 * OOM notifier, but this only prints diagnostic information for the
2321 * current forward-progress test.
2322 */
2323static int rcutorture_oom_notify(struct notifier_block *self,
2324                                 unsigned long notused, void *nfreed)
2325{
2326        struct rcu_fwd *rfp;
2327
2328        mutex_lock(&rcu_fwd_mutex);
2329        rfp = rcu_fwds;
2330        if (!rfp) {
2331                mutex_unlock(&rcu_fwd_mutex);
2332                return NOTIFY_OK;
2333        }
2334        WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
2335             __func__);
2336        rcu_torture_fwd_cb_hist(rfp);
2337        rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
2338        WRITE_ONCE(rcu_fwd_emergency_stop, true);
2339        smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
2340        pr_info("%s: Freed %lu RCU callbacks.\n",
2341                __func__, rcu_torture_fwd_prog_cbfree(rfp));
2342        rcu_barrier();
2343        pr_info("%s: Freed %lu RCU callbacks.\n",
2344                __func__, rcu_torture_fwd_prog_cbfree(rfp));
2345        rcu_barrier();
2346        pr_info("%s: Freed %lu RCU callbacks.\n",
2347                __func__, rcu_torture_fwd_prog_cbfree(rfp));
2348        smp_mb(); /* Frees before return to avoid redoing OOM. */
2349        (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
2350        pr_info("%s returning after OOM processing.\n", __func__);
2351        mutex_unlock(&rcu_fwd_mutex);
2352        return NOTIFY_OK;
2353}
2354
2355static struct notifier_block rcutorture_oom_nb = {
2356        .notifier_call = rcutorture_oom_notify
2357};
2358
2359/* Carry out grace-period forward-progress testing. */
2360static int rcu_torture_fwd_prog(void *args)
2361{
2362        int oldnice = task_nice(current);
2363        struct rcu_fwd *rfp = args;
2364        int tested = 0;
2365        int tested_tries = 0;
2366
2367        VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
2368        rcu_bind_current_to_nocb();
2369        if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
2370                set_user_nice(current, MAX_NICE);
2371        do {
2372                schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
2373                WRITE_ONCE(rcu_fwd_emergency_stop, false);
2374                if (!IS_ENABLED(CONFIG_TINY_RCU) ||
2375                    rcu_inkernel_boot_has_ended())
2376                        rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
2377                if (rcu_inkernel_boot_has_ended())
2378                        rcu_torture_fwd_prog_cr(rfp);
2379
2380                /* Avoid slow periods, better to test when busy. */
2381                if (stutter_wait("rcu_torture_fwd_prog"))
2382                        sched_set_normal(current, oldnice);
2383        } while (!torture_must_stop());
2384        /* Short runs might not contain a valid forward-progress attempt. */
2385        WARN_ON(!tested && tested_tries >= 5);
2386        pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
2387        torture_kthread_stopping("rcu_torture_fwd_prog");
2388        return 0;
2389}
2390
2391/* If forward-progress checking is requested and feasible, spawn the thread. */
2392static int __init rcu_torture_fwd_prog_init(void)
2393{
2394        struct rcu_fwd *rfp;
2395
2396        if (!fwd_progress)
2397                return 0; /* Not requested, so don't do it. */
2398        if ((!cur_ops->sync && !cur_ops->call) ||
2399            !cur_ops->stall_dur || cur_ops->stall_dur() <= 0 || cur_ops == &rcu_busted_ops) {
2400                VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
2401                return 0;
2402        }
2403        if (stall_cpu > 0) {
2404                VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
2405                if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
2406                        return -EINVAL; /* In module, can fail back to user. */
2407                WARN_ON(1); /* Make sure rcutorture notices conflict. */
2408                return 0;
2409        }
2410        if (fwd_progress_holdoff <= 0)
2411                fwd_progress_holdoff = 1;
2412        if (fwd_progress_div <= 0)
2413                fwd_progress_div = 4;
2414        rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
2415        if (!rfp)
2416                return -ENOMEM;
2417        spin_lock_init(&rfp->rcu_fwd_lock);
2418        rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2419        mutex_lock(&rcu_fwd_mutex);
2420        rcu_fwds = rfp;
2421        mutex_unlock(&rcu_fwd_mutex);
2422        register_oom_notifier(&rcutorture_oom_nb);
2423        return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
2424}
2425
2426static void rcu_torture_fwd_prog_cleanup(void)
2427{
2428        struct rcu_fwd *rfp;
2429
2430        torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2431        rfp = rcu_fwds;
2432        mutex_lock(&rcu_fwd_mutex);
2433        rcu_fwds = NULL;
2434        mutex_unlock(&rcu_fwd_mutex);
2435        unregister_oom_notifier(&rcutorture_oom_nb);
2436        kfree(rfp);
2437}
2438
2439/* Callback function for RCU barrier testing. */
2440static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2441{
2442        atomic_inc(&barrier_cbs_invoked);
2443}
2444
2445/* IPI handler to get callback posted on desired CPU, if online. */
2446static void rcu_torture_barrier1cb(void *rcu_void)
2447{
2448        struct rcu_head *rhp = rcu_void;
2449
2450        cur_ops->call(rhp, rcu_torture_barrier_cbf);
2451}
2452
2453/* kthread function to register callbacks used to test RCU barriers. */
2454static int rcu_torture_barrier_cbs(void *arg)
2455{
2456        long myid = (long)arg;
2457        bool lastphase = false;
2458        bool newphase;
2459        struct rcu_head rcu;
2460
2461        init_rcu_head_on_stack(&rcu);
2462        VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2463        set_user_nice(current, MAX_NICE);
2464        do {
2465                wait_event(barrier_cbs_wq[myid],
2466                           (newphase =
2467                            smp_load_acquire(&barrier_phase)) != lastphase ||
2468                           torture_must_stop());
2469                lastphase = newphase;
2470                if (torture_must_stop())
2471                        break;
2472                /*
2473                 * The above smp_load_acquire() ensures barrier_phase load
2474                 * is ordered before the following ->call().
2475                 */
2476                if (smp_call_function_single(myid, rcu_torture_barrier1cb,
2477                                             &rcu, 1)) {
2478                        // IPI failed, so use direct call from current CPU.
2479                        cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2480                }
2481                if (atomic_dec_and_test(&barrier_cbs_count))
2482                        wake_up(&barrier_wq);
2483        } while (!torture_must_stop());
2484        if (cur_ops->cb_barrier != NULL)
2485                cur_ops->cb_barrier();
2486        destroy_rcu_head_on_stack(&rcu);
2487        torture_kthread_stopping("rcu_torture_barrier_cbs");
2488        return 0;
2489}
2490
2491/* kthread function to drive and coordinate RCU barrier testing. */
2492static int rcu_torture_barrier(void *arg)
2493{
2494        int i;
2495
2496        VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2497        do {
2498                atomic_set(&barrier_cbs_invoked, 0);
2499                atomic_set(&barrier_cbs_count, n_barrier_cbs);
2500                /* Ensure barrier_phase ordered after prior assignments. */
2501                smp_store_release(&barrier_phase, !barrier_phase);
2502                for (i = 0; i < n_barrier_cbs; i++)
2503                        wake_up(&barrier_cbs_wq[i]);
2504                wait_event(barrier_wq,
2505                           atomic_read(&barrier_cbs_count) == 0 ||
2506                           torture_must_stop());
2507                if (torture_must_stop())
2508                        break;
2509                n_barrier_attempts++;
2510                cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2511                if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2512                        n_rcu_torture_barrier_error++;
2513                        pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2514                               atomic_read(&barrier_cbs_invoked),
2515                               n_barrier_cbs);
2516                        WARN_ON(1);
2517                        // Wait manually for the remaining callbacks
2518                        i = 0;
2519                        do {
2520                                if (WARN_ON(i++ > HZ))
2521                                        i = INT_MIN;
2522                                schedule_timeout_interruptible(1);
2523                                cur_ops->cb_barrier();
2524                        } while (atomic_read(&barrier_cbs_invoked) !=
2525                                 n_barrier_cbs &&
2526                                 !torture_must_stop());
2527                        smp_mb(); // Can't trust ordering if broken.
2528                        if (!torture_must_stop())
2529                                pr_err("Recovered: barrier_cbs_invoked = %d\n",
2530                                       atomic_read(&barrier_cbs_invoked));
2531                } else {
2532                        n_barrier_successes++;
2533                }
2534                schedule_timeout_interruptible(HZ / 10);
2535        } while (!torture_must_stop());
2536        torture_kthread_stopping("rcu_torture_barrier");
2537        return 0;
2538}
2539
2540/* Initialize RCU barrier testing. */
2541static int rcu_torture_barrier_init(void)
2542{
2543        int i;
2544        int ret;
2545
2546        if (n_barrier_cbs <= 0)
2547                return 0;
2548        if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2549                pr_alert("%s" TORTURE_FLAG
2550                         " Call or barrier ops missing for %s,\n",
2551                         torture_type, cur_ops->name);
2552                pr_alert("%s" TORTURE_FLAG
2553                         " RCU barrier testing omitted from run.\n",
2554                         torture_type);
2555                return 0;
2556        }
2557        atomic_set(&barrier_cbs_count, 0);
2558        atomic_set(&barrier_cbs_invoked, 0);
2559        barrier_cbs_tasks =
2560                kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2561                        GFP_KERNEL);
2562        barrier_cbs_wq =
2563                kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2564        if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2565                return -ENOMEM;
2566        for (i = 0; i < n_barrier_cbs; i++) {
2567                init_waitqueue_head(&barrier_cbs_wq[i]);
2568                ret = torture_create_kthread(rcu_torture_barrier_cbs,
2569                                             (void *)(long)i,
2570                                             barrier_cbs_tasks[i]);
2571                if (ret)
2572                        return ret;
2573        }
2574        return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2575}
2576
2577/* Clean up after RCU barrier testing. */
2578static void rcu_torture_barrier_cleanup(void)
2579{
2580        int i;
2581
2582        torture_stop_kthread(rcu_torture_barrier, barrier_task);
2583        if (barrier_cbs_tasks != NULL) {
2584                for (i = 0; i < n_barrier_cbs; i++)
2585                        torture_stop_kthread(rcu_torture_barrier_cbs,
2586                                             barrier_cbs_tasks[i]);
2587                kfree(barrier_cbs_tasks);
2588                barrier_cbs_tasks = NULL;
2589        }
2590        if (barrier_cbs_wq != NULL) {
2591                kfree(barrier_cbs_wq);
2592                barrier_cbs_wq = NULL;
2593        }
2594}
2595
2596static bool rcu_torture_can_boost(void)
2597{
2598        static int boost_warn_once;
2599        int prio;
2600
2601        if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2602                return false;
2603
2604        prio = rcu_get_gp_kthreads_prio();
2605        if (!prio)
2606                return false;
2607
2608        if (prio < 2) {
2609                if (boost_warn_once  == 1)
2610                        return false;
2611
2612                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);
2613                boost_warn_once = 1;
2614                return false;
2615        }
2616
2617        return true;
2618}
2619
2620static bool read_exit_child_stop;
2621static bool read_exit_child_stopped;
2622static wait_queue_head_t read_exit_wq;
2623
2624// Child kthread which just does an rcutorture reader and exits.
2625static int rcu_torture_read_exit_child(void *trsp_in)
2626{
2627        struct torture_random_state *trsp = trsp_in;
2628
2629        set_user_nice(current, MAX_NICE);
2630        // Minimize time between reading and exiting.
2631        while (!kthread_should_stop())
2632                schedule_timeout_uninterruptible(1);
2633        (void)rcu_torture_one_read(trsp, -1);
2634        return 0;
2635}
2636
2637// Parent kthread which creates and destroys read-exit child kthreads.
2638static int rcu_torture_read_exit(void *unused)
2639{
2640        int count = 0;
2641        bool errexit = false;
2642        int i;
2643        struct task_struct *tsp;
2644        DEFINE_TORTURE_RANDOM(trs);
2645
2646        // Allocate and initialize.
2647        set_user_nice(current, MAX_NICE);
2648        VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of test");
2649
2650        // Each pass through this loop does one read-exit episode.
2651        do {
2652                if (++count > read_exit_burst) {
2653                        VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
2654                        rcu_barrier(); // Wait for task_struct free, avoid OOM.
2655                        for (i = 0; i < read_exit_delay; i++) {
2656                                schedule_timeout_uninterruptible(HZ);
2657                                if (READ_ONCE(read_exit_child_stop))
2658                                        break;
2659                        }
2660                        if (!READ_ONCE(read_exit_child_stop))
2661                                VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
2662                        count = 0;
2663                }
2664                if (READ_ONCE(read_exit_child_stop))
2665                        break;
2666                // Spawn child.
2667                tsp = kthread_run(rcu_torture_read_exit_child,
2668                                     &trs, "%s",
2669                                     "rcu_torture_read_exit_child");
2670                if (IS_ERR(tsp)) {
2671                        VERBOSE_TOROUT_ERRSTRING("out of memory");
2672                        errexit = true;
2673                        tsp = NULL;
2674                        break;
2675                }
2676                cond_resched();
2677                kthread_stop(tsp);
2678                n_read_exits ++;
2679                stutter_wait("rcu_torture_read_exit");
2680        } while (!errexit && !READ_ONCE(read_exit_child_stop));
2681
2682        // Clean up and exit.
2683        smp_store_release(&read_exit_child_stopped, true); // After reaping.
2684        smp_mb(); // Store before wakeup.
2685        wake_up(&read_exit_wq);
2686        while (!torture_must_stop())
2687                schedule_timeout_uninterruptible(1);
2688        torture_kthread_stopping("rcu_torture_read_exit");
2689        return 0;
2690}
2691
2692static int rcu_torture_read_exit_init(void)
2693{
2694        if (read_exit_burst <= 0)
2695                return -EINVAL;
2696        init_waitqueue_head(&read_exit_wq);
2697        read_exit_child_stop = false;
2698        read_exit_child_stopped = false;
2699        return torture_create_kthread(rcu_torture_read_exit, NULL,
2700                                      read_exit_task);
2701}
2702
2703static void rcu_torture_read_exit_cleanup(void)
2704{
2705        if (!read_exit_task)
2706                return;
2707        WRITE_ONCE(read_exit_child_stop, true);
2708        smp_mb(); // Above write before wait.
2709        wait_event(read_exit_wq, smp_load_acquire(&read_exit_child_stopped));
2710        torture_stop_kthread(rcutorture_read_exit, read_exit_task);
2711}
2712
2713static enum cpuhp_state rcutor_hp;
2714
2715static void
2716rcu_torture_cleanup(void)
2717{
2718        int firsttime;
2719        int flags = 0;
2720        unsigned long gp_seq = 0;
2721        int i;
2722
2723        if (torture_cleanup_begin()) {
2724                if (cur_ops->cb_barrier != NULL)
2725                        cur_ops->cb_barrier();
2726                return;
2727        }
2728        if (!cur_ops) {
2729                torture_cleanup_end();
2730                return;
2731        }
2732
2733        if (cur_ops->gp_kthread_dbg)
2734                cur_ops->gp_kthread_dbg();
2735        rcu_torture_read_exit_cleanup();
2736        rcu_torture_barrier_cleanup();
2737        rcu_torture_fwd_prog_cleanup();
2738        torture_stop_kthread(rcu_torture_stall, stall_task);
2739        torture_stop_kthread(rcu_torture_writer, writer_task);
2740
2741        if (nocb_tasks) {
2742                for (i = 0; i < nrealnocbers; i++)
2743                        torture_stop_kthread(rcu_nocb_toggle, nocb_tasks[i]);
2744                kfree(nocb_tasks);
2745                nocb_tasks = NULL;
2746        }
2747
2748        if (reader_tasks) {
2749                for (i = 0; i < nrealreaders; i++)
2750                        torture_stop_kthread(rcu_torture_reader,
2751                                             reader_tasks[i]);
2752                kfree(reader_tasks);
2753                reader_tasks = NULL;
2754        }
2755        kfree(rcu_torture_reader_mbchk);
2756        rcu_torture_reader_mbchk = NULL;
2757
2758        if (fakewriter_tasks) {
2759                for (i = 0; i < nfakewriters; i++)
2760                        torture_stop_kthread(rcu_torture_fakewriter,
2761                                             fakewriter_tasks[i]);
2762                kfree(fakewriter_tasks);
2763                fakewriter_tasks = NULL;
2764        }
2765
2766        rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2767        srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2768        pr_alert("%s:  End-test grace-period state: g%ld f%#x total-gps=%ld\n",
2769                 cur_ops->name, (long)gp_seq, flags,
2770                 rcutorture_seq_diff(gp_seq, start_gp_seq));
2771        torture_stop_kthread(rcu_torture_stats, stats_task);
2772        torture_stop_kthread(rcu_torture_fqs, fqs_task);
2773        if (rcu_torture_can_boost())
2774                cpuhp_remove_state(rcutor_hp);
2775
2776        /*
2777         * Wait for all RCU callbacks to fire, then do torture-type-specific
2778         * cleanup operations.
2779         */
2780        if (cur_ops->cb_barrier != NULL)
2781                cur_ops->cb_barrier();
2782        if (cur_ops->cleanup != NULL)
2783                cur_ops->cleanup();
2784
2785        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2786
2787        if (err_segs_recorded) {
2788                pr_alert("Failure/close-call rcutorture reader segments:\n");
2789                if (rt_read_nsegs == 0)
2790                        pr_alert("\t: No segments recorded!!!\n");
2791                firsttime = 1;
2792                for (i = 0; i < rt_read_nsegs; i++) {
2793                        pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2794                        if (err_segs[i].rt_delay_jiffies != 0) {
2795                                pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2796                                        err_segs[i].rt_delay_jiffies);
2797                                firsttime = 0;
2798                        }
2799                        if (err_segs[i].rt_delay_ms != 0) {
2800                                pr_cont("%s%ldms", firsttime ? "" : "+",
2801                                        err_segs[i].rt_delay_ms);
2802                                firsttime = 0;
2803                        }
2804                        if (err_segs[i].rt_delay_us != 0) {
2805                                pr_cont("%s%ldus", firsttime ? "" : "+",
2806                                        err_segs[i].rt_delay_us);
2807                                firsttime = 0;
2808                        }
2809                        pr_cont("%s\n",
2810                                err_segs[i].rt_preempted ? "preempted" : "");
2811
2812                }
2813        }
2814        if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2815                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2816        else if (torture_onoff_failures())
2817                rcu_torture_print_module_parms(cur_ops,
2818                                               "End of test: RCU_HOTPLUG");
2819        else
2820                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2821        torture_cleanup_end();
2822}
2823
2824#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2825static void rcu_torture_leak_cb(struct rcu_head *rhp)
2826{
2827}
2828
2829static void rcu_torture_err_cb(struct rcu_head *rhp)
2830{
2831        /*
2832         * This -might- happen due to race conditions, but is unlikely.
2833         * The scenario that leads to this happening is that the
2834         * first of the pair of duplicate callbacks is queued,
2835         * someone else starts a grace period that includes that
2836         * callback, then the second of the pair must wait for the
2837         * next grace period.  Unlikely, but can happen.  If it
2838         * does happen, the debug-objects subsystem won't have splatted.
2839         */
2840        pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2841}
2842#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2843
2844/*
2845 * Verify that double-free causes debug-objects to complain, but only
2846 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2847 * cannot be carried out.
2848 */
2849static void rcu_test_debug_objects(void)
2850{
2851#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2852        struct rcu_head rh1;
2853        struct rcu_head rh2;
2854        struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
2855
2856        init_rcu_head_on_stack(&rh1);
2857        init_rcu_head_on_stack(&rh2);
2858        pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2859
2860        /* Try to queue the rh2 pair of callbacks for the same grace period. */
2861        preempt_disable(); /* Prevent preemption from interrupting test. */
2862        rcu_read_lock(); /* Make it impossible to finish a grace period. */
2863        call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2864        local_irq_disable(); /* Make it harder to start a new grace period. */
2865        call_rcu(&rh2, rcu_torture_leak_cb);
2866        call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2867        if (rhp) {
2868                call_rcu(rhp, rcu_torture_leak_cb);
2869                call_rcu(rhp, rcu_torture_err_cb); /* Another duplicate callback. */
2870        }
2871        local_irq_enable();
2872        rcu_read_unlock();
2873        preempt_enable();
2874
2875        /* Wait for them all to get done so we can safely return. */
2876        rcu_barrier();
2877        pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2878        destroy_rcu_head_on_stack(&rh1);
2879        destroy_rcu_head_on_stack(&rh2);
2880#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2881        pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2882#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2883}
2884
2885static void rcutorture_sync(void)
2886{
2887        static unsigned long n;
2888
2889        if (cur_ops->sync && !(++n & 0xfff))
2890                cur_ops->sync();
2891}
2892
2893static int __init
2894rcu_torture_init(void)
2895{
2896        long i;
2897        int cpu;
2898        int firsterr = 0;
2899        int flags = 0;
2900        unsigned long gp_seq = 0;
2901        static struct rcu_torture_ops *torture_ops[] = {
2902                &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2903                &busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
2904                &tasks_tracing_ops, &trivial_ops,
2905        };
2906
2907        if (!torture_init_begin(torture_type, verbose))
2908                return -EBUSY;
2909
2910        /* Process args and tell the world that the torturer is on the job. */
2911        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2912                cur_ops = torture_ops[i];
2913                if (strcmp(torture_type, cur_ops->name) == 0)
2914                        break;
2915        }
2916        if (i == ARRAY_SIZE(torture_ops)) {
2917                pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2918                         torture_type);
2919                pr_alert("rcu-torture types:");
2920                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2921                        pr_cont(" %s", torture_ops[i]->name);
2922                pr_cont("\n");
2923                firsterr = -EINVAL;
2924                cur_ops = NULL;
2925                goto unwind;
2926        }
2927        if (cur_ops->fqs == NULL && fqs_duration != 0) {
2928                pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2929                fqs_duration = 0;
2930        }
2931        if (cur_ops->init)
2932                cur_ops->init();
2933
2934        if (nreaders >= 0) {
2935                nrealreaders = nreaders;
2936        } else {
2937                nrealreaders = num_online_cpus() - 2 - nreaders;
2938                if (nrealreaders <= 0)
2939                        nrealreaders = 1;
2940        }
2941        rcu_torture_print_module_parms(cur_ops, "Start of test");
2942        rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2943        srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2944        start_gp_seq = gp_seq;
2945        pr_alert("%s:  Start-test grace-period state: g%ld f%#x\n",
2946                 cur_ops->name, (long)gp_seq, flags);
2947
2948        /* Set up the freelist. */
2949
2950        INIT_LIST_HEAD(&rcu_torture_freelist);
2951        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2952                rcu_tortures[i].rtort_mbtest = 0;
2953                list_add_tail(&rcu_tortures[i].rtort_free,
2954                              &rcu_torture_freelist);
2955        }
2956
2957        /* Initialize the statistics so that each run gets its own numbers. */
2958
2959        rcu_torture_current = NULL;
2960        rcu_torture_current_version = 0;
2961        atomic_set(&n_rcu_torture_alloc, 0);
2962        atomic_set(&n_rcu_torture_alloc_fail, 0);
2963        atomic_set(&n_rcu_torture_free, 0);
2964        atomic_set(&n_rcu_torture_mberror, 0);
2965        atomic_set(&n_rcu_torture_mbchk_fail, 0);
2966        atomic_set(&n_rcu_torture_mbchk_tries, 0);
2967        atomic_set(&n_rcu_torture_error, 0);
2968        n_rcu_torture_barrier_error = 0;
2969        n_rcu_torture_boost_ktrerror = 0;
2970        n_rcu_torture_boost_rterror = 0;
2971        n_rcu_torture_boost_failure = 0;
2972        n_rcu_torture_boosts = 0;
2973        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2974                atomic_set(&rcu_torture_wcount[i], 0);
2975        for_each_possible_cpu(cpu) {
2976                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2977                        per_cpu(rcu_torture_count, cpu)[i] = 0;
2978                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
2979                }
2980        }
2981        err_segs_recorded = 0;
2982        rt_read_nsegs = 0;
2983
2984        /* Start up the kthreads. */
2985
2986        rcu_torture_write_types();
2987        firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2988                                          writer_task);
2989        if (firsterr)
2990                goto unwind;
2991        if (nfakewriters > 0) {
2992                fakewriter_tasks = kcalloc(nfakewriters,
2993                                           sizeof(fakewriter_tasks[0]),
2994                                           GFP_KERNEL);
2995                if (fakewriter_tasks == NULL) {
2996                        VERBOSE_TOROUT_ERRSTRING("out of memory");
2997                        firsterr = -ENOMEM;
2998                        goto unwind;
2999                }
3000        }
3001        for (i = 0; i < nfakewriters; i++) {
3002                firsterr = torture_create_kthread(rcu_torture_fakewriter,
3003                                                  NULL, fakewriter_tasks[i]);
3004                if (firsterr)
3005                        goto unwind;
3006        }
3007        reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
3008                               GFP_KERNEL);
3009        rcu_torture_reader_mbchk = kcalloc(nrealreaders, sizeof(*rcu_torture_reader_mbchk),
3010                                           GFP_KERNEL);
3011        if (!reader_tasks || !rcu_torture_reader_mbchk) {
3012                VERBOSE_TOROUT_ERRSTRING("out of memory");
3013                firsterr = -ENOMEM;
3014                goto unwind;
3015        }
3016        for (i = 0; i < nrealreaders; i++) {
3017                rcu_torture_reader_mbchk[i].rtc_chkrdr = -1;
3018                firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
3019                                                  reader_tasks[i]);
3020                if (firsterr)
3021                        goto unwind;
3022        }
3023        nrealnocbers = nocbs_nthreads;
3024        if (WARN_ON(nrealnocbers < 0))
3025                nrealnocbers = 1;
3026        if (WARN_ON(nocbs_toggle < 0))
3027                nocbs_toggle = HZ;
3028        if (nrealnocbers > 0) {
3029                nocb_tasks = kcalloc(nrealnocbers, sizeof(nocb_tasks[0]), GFP_KERNEL);
3030                if (nocb_tasks == NULL) {
3031                        VERBOSE_TOROUT_ERRSTRING("out of memory");
3032                        firsterr = -ENOMEM;
3033                        goto unwind;
3034                }
3035        } else {
3036                nocb_tasks = NULL;
3037        }
3038        for (i = 0; i < nrealnocbers; i++) {
3039                firsterr = torture_create_kthread(rcu_nocb_toggle, NULL, nocb_tasks[i]);
3040                if (firsterr)
3041                        goto unwind;
3042        }
3043        if (stat_interval > 0) {
3044                firsterr = torture_create_kthread(rcu_torture_stats, NULL,
3045                                                  stats_task);
3046                if (firsterr)
3047                        goto unwind;
3048        }
3049        if (test_no_idle_hz && shuffle_interval > 0) {
3050                firsterr = torture_shuffle_init(shuffle_interval * HZ);
3051                if (firsterr)
3052                        goto unwind;
3053        }
3054        if (stutter < 0)
3055                stutter = 0;
3056        if (stutter) {
3057                int t;
3058
3059                t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
3060                firsterr = torture_stutter_init(stutter * HZ, t);
3061                if (firsterr)
3062                        goto unwind;
3063        }
3064        if (fqs_duration < 0)
3065                fqs_duration = 0;
3066        if (fqs_duration) {
3067                /* Create the fqs thread */
3068                firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
3069                                                  fqs_task);
3070                if (firsterr)
3071                        goto unwind;
3072        }
3073        if (test_boost_interval < 1)
3074                test_boost_interval = 1;
3075        if (test_boost_duration < 2)
3076                test_boost_duration = 2;
3077        if (rcu_torture_can_boost()) {
3078
3079                boost_starttime = jiffies + test_boost_interval * HZ;
3080
3081                firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
3082                                             rcutorture_booster_init,
3083                                             rcutorture_booster_cleanup);
3084                if (firsterr < 0)
3085                        goto unwind;
3086                rcutor_hp = firsterr;
3087        }
3088        shutdown_jiffies = jiffies + shutdown_secs * HZ;
3089        firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
3090        if (firsterr)
3091                goto unwind;
3092        firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
3093                                      rcutorture_sync);
3094        if (firsterr)
3095                goto unwind;
3096        firsterr = rcu_torture_stall_init();
3097        if (firsterr)
3098                goto unwind;
3099        firsterr = rcu_torture_fwd_prog_init();
3100        if (firsterr)
3101                goto unwind;
3102        firsterr = rcu_torture_barrier_init();
3103        if (firsterr)
3104                goto unwind;
3105        firsterr = rcu_torture_read_exit_init();
3106        if (firsterr)
3107                goto unwind;
3108        if (object_debug)
3109                rcu_test_debug_objects();
3110        torture_init_end();
3111        return 0;
3112
3113unwind:
3114        torture_init_end();
3115        rcu_torture_cleanup();
3116        if (shutdown_secs) {
3117                WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
3118                kernel_power_off();
3119        }
3120        return firsterr;
3121}
3122
3123module_init(rcu_torture_init);
3124module_exit(rcu_torture_cleanup);
3125