kernel/rcu/rcutorture.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based torture test facility
   4  *
   5  * Copyright (C) IBM Corporation, 2005, 2006
   6  *
   7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8  *        Josh Triplett <josh@joshtriplett.org>
   9  *
  10  * See also:  Documentation/RCU/torture.txt
  11  */
  12
  13 #define pr_fmt(fmt) fmt
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/kthread.h>
  20 #include <linux/err.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/smp.h>
  23 #include <linux/rcupdate.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/sched/signal.h>
  26 #include <uapi/linux/sched/types.h>
  27 #include <linux/atomic.h>
  28 #include <linux/bitops.h>
  29 #include <linux/completion.h>
  30 #include <linux/moduleparam.h>
  31 #include <linux/percpu.h>
  32 #include <linux/notifier.h>
  33 #include <linux/reboot.h>
  34 #include <linux/freezer.h>
  35 #include <linux/cpu.h>
  36 #include <linux/delay.h>
  37 #include <linux/stat.h>
  38 #include <linux/srcu.h>
  39 #include <linux/slab.h>
  40 #include <linux/trace_clock.h>
  41 #include <asm/byteorder.h>
  42 #include <linux/torture.h>
  43 #include <linux/vmalloc.h>
  44 #include <linux/sched/debug.h>
  45 #include <linux/sched/sysctl.h>
  46 #include <linux/oom.h>
  47
  48 #include "rcu.h"
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  52
  53
  54 /* Bits for ->extendables field, extendables param, and related definitions. */
  55 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  56 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  57 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  58 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  59 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  60 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  61 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  62 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  63 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  64 #define RCUTORTURE_MAX_EXTEND    \
  65         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  66          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  67 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  68                                         /* Must be power of two minus one. */
  69 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  70
  71 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  72               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  73 torture_param(int, fqs_duration, 0,
  74               "Duration of fqs bursts (us), 0 to disable");
  75 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  76 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  77 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  78 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  79 torture_param(int, fwd_progress_holdoff, 60,
  80               "Time between forward-progress tests (s)");
  81 torture_param(bool, fwd_progress_need_resched, 1,
  82               "Hide cond_resched() behind need_resched()");
  83 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  84 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  85 torture_param(bool, gp_normal, false,
  86              "Use normal (non-expedited) GP wait primitives");
  87 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  88 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  89 torture_param(int, n_barrier_cbs, 0,
  90              "# of callbacks/kthreads for barrier testing");
  91 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  92 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  93 torture_param(int, object_debug, 0,
  94              "Enable debug-object double call_rcu() testing");
  95 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  96 torture_param(int, onoff_interval, 0,
  97              "Time between CPU hotplugs (jiffies), 0=disable");
  98 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  99 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 100 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 101 torture_param(int, stall_cpu_holdoff, 10,
 102              "Time to wait before starting stall (s).");
 103 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 104 torture_param(int, stat_interval, 60,
 105              "Number of seconds between stats printk()s");
 106 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 107 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 108 torture_param(int, test_boost_duration, 4,
 109              "Duration of each boost test, seconds.");
 110 torture_param(int, test_boost_interval, 7,
 111              "Interval between boost tests, seconds.");
 112 torture_param(bool, test_no_idle_hz, true,
 113              "Test support for tickless idle CPUs");
 114 torture_param(int, verbose, 1,
 115              "Enable verbose debugging printk()s");
 116
 117 static char *torture_type = "rcu";
 118 module_param(torture_type, charp, 0444);
 119 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 120
 121 static int nrealreaders;
 122 static struct task_struct *writer_task;
 123 static struct task_struct **fakewriter_tasks;
 124 static struct task_struct **reader_tasks;
 125 static struct task_struct *stats_task;
 126 static struct task_struct *fqs_task;
 127 static struct task_struct *boost_tasks[NR_CPUS];
 128 static struct task_struct *stall_task;
 129 static struct task_struct *fwd_prog_task;
 130 static struct task_struct **barrier_cbs_tasks;
 131 static struct task_struct *barrier_task;
 132
 133 #define RCU_TORTURE_PIPE_LEN 10
 134
 135 struct rcu_torture {
 136         struct rcu_head rtort_rcu;
 137         int rtort_pipe_count;
 138         struct list_head rtort_free;
 139         int rtort_mbtest;
 140 };
 141
 142 static LIST_HEAD(rcu_torture_freelist);
 143 static struct rcu_torture __rcu *rcu_torture_current;
 144 static unsigned long rcu_torture_current_version;
 145 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 146 static DEFINE_SPINLOCK(rcu_torture_lock);
 147 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 148 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 149 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 150 static atomic_t n_rcu_torture_alloc;
 151 static atomic_t n_rcu_torture_alloc_fail;
 152 static atomic_t n_rcu_torture_free;
 153 static atomic_t n_rcu_torture_mberror;
 154 static atomic_t n_rcu_torture_error;
 155 static long n_rcu_torture_barrier_error;
 156 static long n_rcu_torture_boost_ktrerror;
 157 static long n_rcu_torture_boost_rterror;
 158 static long n_rcu_torture_boost_failure;
 159 static long n_rcu_torture_boosts;
 160 static atomic_long_t n_rcu_torture_timers;
 161 static long n_barrier_attempts;
 162 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 163 static struct list_head rcu_torture_removed;
 164
 165 static int rcu_torture_writer_state;
 166 #define RTWS_FIXED_DELAY        0
 167 #define RTWS_DELAY              1
 168 #define RTWS_REPLACE            2
 169 #define RTWS_DEF_FREE           3
 170 #define RTWS_EXP_SYNC           4
 171 #define RTWS_COND_GET           5
 172 #define RTWS_COND_SYNC          6
 173 #define RTWS_SYNC               7
 174 #define RTWS_STUTTER            8
 175 #define RTWS_STOPPING           9
 176 static const char * const rcu_torture_writer_state_names[] = {
 177         "RTWS_FIXED_DELAY",
 178         "RTWS_DELAY",
 179         "RTWS_REPLACE",
 180         "RTWS_DEF_FREE",
 181         "RTWS_EXP_SYNC",
 182         "RTWS_COND_GET",
 183         "RTWS_COND_SYNC",
 184         "RTWS_SYNC",
 185         "RTWS_STUTTER",
 186         "RTWS_STOPPING",
 187 };
 188
 189 /* Record reader segment types and duration for first failing read. */
 190 struct rt_read_seg {
 191         int rt_readstate;
 192         unsigned long rt_delay_jiffies;
 193         unsigned long rt_delay_ms;
 194         unsigned long rt_delay_us;
 195         bool rt_preempted;
 196 };
 197 static int err_segs_recorded;
 198 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 199 static int rt_read_nsegs;
 200
 201 static const char *rcu_torture_writer_state_getname(void)
 202 {
 203         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 204
 205         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 206                 return "???";
 207         return rcu_torture_writer_state_names[i];
 208 }
 209
 210 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 211 #define rcu_can_boost() 1
 212 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 213 #define rcu_can_boost() 0
 214 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 215
 216 #ifdef CONFIG_RCU_TRACE
 217 static u64 notrace rcu_trace_clock_local(void)
 218 {
 219         u64 ts = trace_clock_local();
 220
 221         (void)do_div(ts, NSEC_PER_USEC);
 222         return ts;
 223 }
 224 #else /* #ifdef CONFIG_RCU_TRACE */
 225 static u64 notrace rcu_trace_clock_local(void)
 226 {
 227         return 0ULL;
 228 }
 229 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 230
 231 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 232 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 233                                         /*  and boost task create/destroy. */
 234 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 235 static bool barrier_phase;              /* Test phase. */
 236 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 237 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 238 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 239
 240 static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 241
 242 /*
 243  * Allocate an element from the rcu_tortures pool.
 244  */
 245 static struct rcu_torture *
 246 rcu_torture_alloc(void)
 247 {
 248         struct list_head *p;
 249
 250         spin_lock_bh(&rcu_torture_lock);
 251         if (list_empty(&rcu_torture_freelist)) {
 252                 atomic_inc(&n_rcu_torture_alloc_fail);
 253                 spin_unlock_bh(&rcu_torture_lock);
 254                 return NULL;
 255         }
 256         atomic_inc(&n_rcu_torture_alloc);
 257         p = rcu_torture_freelist.next;
 258         list_del_init(p);
 259         spin_unlock_bh(&rcu_torture_lock);
 260         return container_of(p, struct rcu_torture, rtort_free);
 261 }
 262
 263 /*
 264  * Free an element to the rcu_tortures pool.
 265  */
 266 static void
 267 rcu_torture_free(struct rcu_torture *p)
 268 {
 269         atomic_inc(&n_rcu_torture_free);
 270         spin_lock_bh(&rcu_torture_lock);
 271         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 272         spin_unlock_bh(&rcu_torture_lock);
 273 }
 274
 275 /*
 276  * Operations vector for selecting different types of tests.
 277  */
 278
 279 struct rcu_torture_ops {
 280         int ttype;
 281         void (*init)(void);
 282         void (*cleanup)(void);
 283         int (*readlock)(void);
 284         void (*read_delay)(struct torture_random_state *rrsp,
 285                            struct rt_read_seg *rtrsp);
 286         void (*readunlock)(int idx);
 287         unsigned long (*get_gp_seq)(void);
 288         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 289         void (*deferred_free)(struct rcu_torture *p);
 290         void (*sync)(void);
 291         void (*exp_sync)(void);
 292         unsigned long (*get_state)(void);
 293         void (*cond_sync)(unsigned long oldstate);
 294         call_rcu_func_t call;
 295         void (*cb_barrier)(void);
 296         void (*fqs)(void);
 297         void (*stats)(void);
 298         int (*stall_dur)(void);
 299         int irq_capable;
 300         int can_boost;
 301         int extendables;
 302         const char *name;
 303 };
 304
 305 static struct rcu_torture_ops *cur_ops;
 306
 307 /*
 308  * Definitions for rcu torture testing.
 309  */
 310
 311 static int rcu_torture_read_lock(void) __acquires(RCU)
 312 {
 313         rcu_read_lock();
 314         return 0;
 315 }
 316
 317 static void
 318 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 319 {
 320         unsigned long started;
 321         unsigned long completed;
 322         const unsigned long shortdelay_us = 200;
 323         unsigned long longdelay_ms = 300;
 324         unsigned long long ts;
 325
 326         /* We want a short delay sometimes to make a reader delay the grace
 327          * period, and we want a long delay occasionally to trigger
 328          * force_quiescent_state. */
 329
 330         if (!rcu_fwd_cb_nodelay &&
 331             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 332                 started = cur_ops->get_gp_seq();
 333                 ts = rcu_trace_clock_local();
 334                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 335                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 336                 mdelay(longdelay_ms);
 337                 rtrsp->rt_delay_ms = longdelay_ms;
 338                 completed = cur_ops->get_gp_seq();
 339                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 340                                           started, completed);
 341         }
 342         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 343                 udelay(shortdelay_us);
 344                 rtrsp->rt_delay_us = shortdelay_us;
 345         }
 346         if (!preempt_count() &&
 347             !(torture_random(rrsp) % (nrealreaders * 500))) {
 348                 torture_preempt_schedule();  /* QS only if preemptible. */
 349                 rtrsp->rt_preempted = true;
 350         }
 351 }
 352
 353 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 354 {
 355         rcu_read_unlock();
 356 }
 357
 358 /*
 359  * Update callback in the pipe.  This should be invoked after a grace period.
 360  */
 361 static bool
 362 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 363 {
 364         int i;
 365
 366         i = rp->rtort_pipe_count;
 367         if (i > RCU_TORTURE_PIPE_LEN)
 368                 i = RCU_TORTURE_PIPE_LEN;
 369         atomic_inc(&rcu_torture_wcount[i]);
 370         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 371                 rp->rtort_mbtest = 0;
 372                 return true;
 373         }
 374         return false;
 375 }
 376
 377 /*
 378  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 379  * primitives.
 380  */
 381 static void
 382 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 383 {
 384         struct rcu_torture *rp;
 385         struct rcu_torture *rp1;
 386
 387         if (old_rp)
 388                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 389         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 390                 if (rcu_torture_pipe_update_one(rp)) {
 391                         list_del(&rp->rtort_free);
 392                         rcu_torture_free(rp);
 393                 }
 394         }
 395 }
 396
 397 static void
 398 rcu_torture_cb(struct rcu_head *p)
 399 {
 400         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 401
 402         if (torture_must_stop_irq()) {
 403                 /* Test is ending, just drop callbacks on the floor. */
 404                 /* The next initialization will pick up the pieces. */
 405                 return;
 406         }
 407         if (rcu_torture_pipe_update_one(rp))
 408                 rcu_torture_free(rp);
 409         else
 410                 cur_ops->deferred_free(rp);
 411 }
 412
 413 static unsigned long rcu_no_completed(void)
 414 {
 415         return 0;
 416 }
 417
 418 static void rcu_torture_deferred_free(struct rcu_torture *p)
 419 {
 420         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 421 }
 422
 423 static void rcu_sync_torture_init(void)
 424 {
 425         INIT_LIST_HEAD(&rcu_torture_removed);
 426 }
 427
 428 static struct rcu_torture_ops rcu_ops = {
 429         .ttype          = RCU_FLAVOR,
 430         .init           = rcu_sync_torture_init,
 431         .readlock       = rcu_torture_read_lock,
 432         .read_delay     = rcu_read_delay,
 433         .readunlock     = rcu_torture_read_unlock,
 434         .get_gp_seq     = rcu_get_gp_seq,
 435         .gp_diff        = rcu_seq_diff,
 436         .deferred_free  = rcu_torture_deferred_free,
 437         .sync           = synchronize_rcu,
 438         .exp_sync       = synchronize_rcu_expedited,
 439         .get_state      = get_state_synchronize_rcu,
 440         .cond_sync      = cond_synchronize_rcu,
 441         .call           = call_rcu,
 442         .cb_barrier     = rcu_barrier,
 443         .fqs            = rcu_force_quiescent_state,
 444         .stats          = NULL,
 445         .stall_dur      = rcu_jiffies_till_stall_check,
 446         .irq_capable    = 1,
 447         .can_boost      = rcu_can_boost(),
 448         .extendables    = RCUTORTURE_MAX_EXTEND,
 449         .name           = "rcu"
 450 };
 451
 452 /*
 453  * Don't even think about trying any of these in real life!!!
 454  * The names includes "busted", and they really means it!
 455  * The only purpose of these functions is to provide a buggy RCU
 456  * implementation to make sure that rcutorture correctly emits
 457  * buggy-RCU error messages.
 458  */
 459 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 460 {
 461         /* This is a deliberate bug for testing purposes only! */
 462         rcu_torture_cb(&p->rtort_rcu);
 463 }
 464
 465 static void synchronize_rcu_busted(void)
 466 {
 467         /* This is a deliberate bug for testing purposes only! */
 468 }
 469
 470 static void
 471 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 472 {
 473         /* This is a deliberate bug for testing purposes only! */
 474         func(head);
 475 }
 476
 477 static struct rcu_torture_ops rcu_busted_ops = {
 478         .ttype          = INVALID_RCU_FLAVOR,
 479         .init           = rcu_sync_torture_init,
 480         .readlock       = rcu_torture_read_lock,
 481         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 482         .readunlock     = rcu_torture_read_unlock,
 483         .get_gp_seq     = rcu_no_completed,
 484         .deferred_free  = rcu_busted_torture_deferred_free,
 485         .sync           = synchronize_rcu_busted,
 486         .exp_sync       = synchronize_rcu_busted,
 487         .call           = call_rcu_busted,
 488         .cb_barrier     = NULL,
 489         .fqs            = NULL,
 490         .stats          = NULL,
 491         .irq_capable    = 1,
 492         .name           = "busted"
 493 };
 494
 495 /*
 496  * Definitions for srcu torture testing.
 497  */
 498
 499 DEFINE_STATIC_SRCU(srcu_ctl);
 500 static struct srcu_struct srcu_ctld;
 501 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 502
 503 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 504 {
 505         return srcu_read_lock(srcu_ctlp);
 506 }
 507
 508 static void
 509 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 510 {
 511         long delay;
 512         const long uspertick = 1000000 / HZ;
 513         const long longdelay = 10;
 514
 515         /* We want there to be long-running readers, but not all the time. */
 516
 517         delay = torture_random(rrsp) %
 518                 (nrealreaders * 2 * longdelay * uspertick);
 519         if (!delay && in_task()) {
 520                 schedule_timeout_interruptible(longdelay);
 521                 rtrsp->rt_delay_jiffies = longdelay;
 522         } else {
 523                 rcu_read_delay(rrsp, rtrsp);
 524         }
 525 }
 526
 527 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 528 {
 529         srcu_read_unlock(srcu_ctlp, idx);
 530 }
 531
 532 static unsigned long srcu_torture_completed(void)
 533 {
 534         return srcu_batches_completed(srcu_ctlp);
 535 }
 536
 537 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 538 {
 539         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 540 }
 541
 542 static void srcu_torture_synchronize(void)
 543 {
 544         synchronize_srcu(srcu_ctlp);
 545 }
 546
 547 static void srcu_torture_call(struct rcu_head *head,
 548                               rcu_callback_t func)
 549 {
 550         call_srcu(srcu_ctlp, head, func);
 551 }
 552
 553 static void srcu_torture_barrier(void)
 554 {
 555         srcu_barrier(srcu_ctlp);
 556 }
 557
 558 static void srcu_torture_stats(void)
 559 {
 560         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 561 }
 562
 563 static void srcu_torture_synchronize_expedited(void)
 564 {
 565         synchronize_srcu_expedited(srcu_ctlp);
 566 }
 567
 568 static struct rcu_torture_ops srcu_ops = {
 569         .ttype          = SRCU_FLAVOR,
 570         .init           = rcu_sync_torture_init,
 571         .readlock       = srcu_torture_read_lock,
 572         .read_delay     = srcu_read_delay,
 573         .readunlock     = srcu_torture_read_unlock,
 574         .get_gp_seq     = srcu_torture_completed,
 575         .deferred_free  = srcu_torture_deferred_free,
 576         .sync           = srcu_torture_synchronize,
 577         .exp_sync       = srcu_torture_synchronize_expedited,
 578         .call           = srcu_torture_call,
 579         .cb_barrier     = srcu_torture_barrier,
 580         .stats          = srcu_torture_stats,
 581         .irq_capable    = 1,
 582         .name           = "srcu"
 583 };
 584
 585 static void srcu_torture_init(void)
 586 {
 587         rcu_sync_torture_init();
 588         WARN_ON(init_srcu_struct(&srcu_ctld));
 589         srcu_ctlp = &srcu_ctld;
 590 }
 591
 592 static void srcu_torture_cleanup(void)
 593 {
 594         cleanup_srcu_struct(&srcu_ctld);
 595         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 596 }
 597
 598 /* As above, but dynamically allocated. */
 599 static struct rcu_torture_ops srcud_ops = {
 600         .ttype          = SRCU_FLAVOR,
 601         .init           = srcu_torture_init,
 602         .cleanup        = srcu_torture_cleanup,
 603         .readlock       = srcu_torture_read_lock,
 604         .read_delay     = srcu_read_delay,
 605         .readunlock     = srcu_torture_read_unlock,
 606         .get_gp_seq     = srcu_torture_completed,
 607         .deferred_free  = srcu_torture_deferred_free,
 608         .sync           = srcu_torture_synchronize,
 609         .exp_sync       = srcu_torture_synchronize_expedited,
 610         .call           = srcu_torture_call,
 611         .cb_barrier     = srcu_torture_barrier,
 612         .stats          = srcu_torture_stats,
 613         .irq_capable    = 1,
 614         .name           = "srcud"
 615 };
 616
 617 /* As above, but broken due to inappropriate reader extension. */
 618 static struct rcu_torture_ops busted_srcud_ops = {
 619         .ttype          = SRCU_FLAVOR,
 620         .init           = srcu_torture_init,
 621         .cleanup        = srcu_torture_cleanup,
 622         .readlock       = srcu_torture_read_lock,
 623         .read_delay     = rcu_read_delay,
 624         .readunlock     = srcu_torture_read_unlock,
 625         .get_gp_seq     = srcu_torture_completed,
 626         .deferred_free  = srcu_torture_deferred_free,
 627         .sync           = srcu_torture_synchronize,
 628         .exp_sync       = srcu_torture_synchronize_expedited,
 629         .call           = srcu_torture_call,
 630         .cb_barrier     = srcu_torture_barrier,
 631         .stats          = srcu_torture_stats,
 632         .irq_capable    = 1,
 633         .extendables    = RCUTORTURE_MAX_EXTEND,
 634         .name           = "busted_srcud"
 635 };
 636
 637 /*
 638  * Definitions for RCU-tasks torture testing.
 639  */
 640
 641 static int tasks_torture_read_lock(void)
 642 {
 643         return 0;
 644 }
 645
 646 static void tasks_torture_read_unlock(int idx)
 647 {
 648 }
 649
 650 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 651 {
 652         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 653 }
 654
 655 static struct rcu_torture_ops tasks_ops = {
 656         .ttype          = RCU_TASKS_FLAVOR,
 657         .init           = rcu_sync_torture_init,
 658         .readlock       = tasks_torture_read_lock,
 659         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 660         .readunlock     = tasks_torture_read_unlock,
 661         .get_gp_seq     = rcu_no_completed,
 662         .deferred_free  = rcu_tasks_torture_deferred_free,
 663         .sync           = synchronize_rcu_tasks,
 664         .exp_sync       = synchronize_rcu_tasks,
 665         .call           = call_rcu_tasks,
 666         .cb_barrier     = rcu_barrier_tasks,
 667         .fqs            = NULL,
 668         .stats          = NULL,
 669         .irq_capable    = 1,
 670         .name           = "tasks"
 671 };
 672
 673 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 674 {
 675         if (!cur_ops->gp_diff)
 676                 return new - old;
 677         return cur_ops->gp_diff(new, old);
 678 }
 679
 680 static bool __maybe_unused torturing_tasks(void)
 681 {
 682         return cur_ops == &tasks_ops;
 683 }
 684
 685 /*
 686  * RCU torture priority-boost testing.  Runs one real-time thread per
 687  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 688  * spinning waiting for them to be invoked.  If a given callback takes
 689  * too long to be invoked, we assume that priority inversion has occurred.
 690  */
 691
 692 struct rcu_boost_inflight {
 693         struct rcu_head rcu;
 694         int inflight;
 695 };
 696
 697 static void rcu_torture_boost_cb(struct rcu_head *head)
 698 {
 699         struct rcu_boost_inflight *rbip =
 700                 container_of(head, struct rcu_boost_inflight, rcu);
 701
 702         /* Ensure RCU-core accesses precede clearing ->inflight */
 703         smp_store_release(&rbip->inflight, 0);
 704 }
 705
 706 static int old_rt_runtime = -1;
 707
 708 static void rcu_torture_disable_rt_throttle(void)
 709 {
 710         /*
 711          * Disable RT throttling so that rcutorture's boost threads don't get
 712          * throttled. Only possible if rcutorture is built-in otherwise the
 713          * user should manually do this by setting the sched_rt_period_us and
 714          * sched_rt_runtime sysctls.
 715          */
 716         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 717                 return;
 718
 719         old_rt_runtime = sysctl_sched_rt_runtime;
 720         sysctl_sched_rt_runtime = -1;
 721 }
 722
 723 static void rcu_torture_enable_rt_throttle(void)
 724 {
 725         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 726                 return;
 727
 728         sysctl_sched_rt_runtime = old_rt_runtime;
 729         old_rt_runtime = -1;
 730 }
 731
 732 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 733 {
 734         if (end - start > test_boost_duration * HZ - HZ / 2) {
 735                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 736                 n_rcu_torture_boost_failure++;
 737
 738                 return true; /* failed */
 739         }
 740
 741         return false; /* passed */
 742 }
 743
 744 static int rcu_torture_boost(void *arg)
 745 {
 746         unsigned long call_rcu_time;
 747         unsigned long endtime;
 748         unsigned long oldstarttime;
 749         struct rcu_boost_inflight rbi = { .inflight = 0 };
 750         struct sched_param sp;
 751
 752         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 753
 754         /* Set real-time priority. */
 755         sp.sched_priority = 1;
 756         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 757                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 758                 n_rcu_torture_boost_rterror++;
 759         }
 760
 761         init_rcu_head_on_stack(&rbi.rcu);
 762         /* Each pass through the following loop does one boost-test cycle. */
 763         do {
 764                 /* Track if the test failed already in this test interval? */
 765                 bool failed = false;
 766
 767                 /* Increment n_rcu_torture_boosts once per boost-test */
 768                 while (!kthread_should_stop()) {
 769                         if (mutex_trylock(&boost_mutex)) {
 770                                 n_rcu_torture_boosts++;
 771                                 mutex_unlock(&boost_mutex);
 772                                 break;
 773                         }
 774                         schedule_timeout_uninterruptible(1);
 775                 }
 776                 if (kthread_should_stop())
 777                         goto checkwait;
 778
 779                 /* Wait for the next test interval. */
 780                 oldstarttime = boost_starttime;
 781                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 782                         schedule_timeout_interruptible(oldstarttime - jiffies);
 783                         stutter_wait("rcu_torture_boost");
 784                         if (torture_must_stop())
 785                                 goto checkwait;
 786                 }
 787
 788                 /* Do one boost-test interval. */
 789                 endtime = oldstarttime + test_boost_duration * HZ;
 790                 call_rcu_time = jiffies;
 791                 while (ULONG_CMP_LT(jiffies, endtime)) {
 792                         /* If we don't have a callback in flight, post one. */
 793                         if (!smp_load_acquire(&rbi.inflight)) {
 794                                 /* RCU core before ->inflight = 1. */
 795                                 smp_store_release(&rbi.inflight, 1);
 796                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 797                                 /* Check if the boost test failed */
 798                                 failed = failed ||
 799                                          rcu_torture_boost_failed(call_rcu_time,
 800                                                                  jiffies);
 801                                 call_rcu_time = jiffies;
 802                         }
 803                         stutter_wait("rcu_torture_boost");
 804                         if (torture_must_stop())
 805                                 goto checkwait;
 806                 }
 807
 808                 /*
 809                  * If boost never happened, then inflight will always be 1, in
 810                  * this case the boost check would never happen in the above
 811                  * loop so do another one here.
 812                  */
 813                 if (!failed && smp_load_acquire(&rbi.inflight))
 814                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 815
 816                 /*
 817                  * Set the start time of the next test interval.
 818                  * Yes, this is vulnerable to long delays, but such
 819                  * delays simply cause a false negative for the next
 820                  * interval.  Besides, we are running at RT priority,
 821                  * so delays should be relatively rare.
 822                  */
 823                 while (oldstarttime == boost_starttime &&
 824                        !kthread_should_stop()) {
 825                         if (mutex_trylock(&boost_mutex)) {
 826                                 boost_starttime = jiffies +
 827                                                   test_boost_interval * HZ;
 828                                 mutex_unlock(&boost_mutex);
 829                                 break;
 830                         }
 831                         schedule_timeout_uninterruptible(1);
 832                 }
 833
 834                 /* Go do the stutter. */
 835 checkwait:      stutter_wait("rcu_torture_boost");
 836         } while (!torture_must_stop());
 837
 838         /* Clean up and exit. */
 839         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 840                 torture_shutdown_absorb("rcu_torture_boost");
 841                 schedule_timeout_uninterruptible(1);
 842         }
 843         destroy_rcu_head_on_stack(&rbi.rcu);
 844         torture_kthread_stopping("rcu_torture_boost");
 845         return 0;
 846 }
 847
 848 /*
 849  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 850  * bursts of calls to force_quiescent_state(), increasing the probability
 851  * of occurrence of some important types of race conditions.
 852  */
 853 static int
 854 rcu_torture_fqs(void *arg)
 855 {
 856         unsigned long fqs_resume_time;
 857         int fqs_burst_remaining;
 858
 859         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 860         do {
 861                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 862                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 863                        !kthread_should_stop()) {
 864                         schedule_timeout_interruptible(1);
 865                 }
 866                 fqs_burst_remaining = fqs_duration;
 867                 while (fqs_burst_remaining > 0 &&
 868                        !kthread_should_stop()) {
 869                         cur_ops->fqs();
 870                         udelay(fqs_holdoff);
 871                         fqs_burst_remaining -= fqs_holdoff;
 872                 }
 873                 stutter_wait("rcu_torture_fqs");
 874         } while (!torture_must_stop());
 875         torture_kthread_stopping("rcu_torture_fqs");
 876         return 0;
 877 }
 878
 879 /*
 880  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 881  * for that pointed to by rcu_torture_current, freeing the old structure
 882  * after a series of grace periods (the "pipeline").
 883  */
 884 static int
 885 rcu_torture_writer(void *arg)
 886 {
 887         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 888         int expediting = 0;
 889         unsigned long gp_snap;
 890         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 891         bool gp_sync1 = gp_sync;
 892         int i;
 893         struct rcu_torture *rp;
 894         struct rcu_torture *old_rp;
 895         static DEFINE_TORTURE_RANDOM(rand);
 896         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 897                            RTWS_COND_GET, RTWS_SYNC };
 898         int nsynctypes = 0;
 899
 900         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 901         if (!can_expedite)
 902                 pr_alert("%s" TORTURE_FLAG
 903                          " GP expediting controlled from boot/sysfs for %s.\n",
 904                          torture_type, cur_ops->name);
 905
 906         /* Initialize synctype[] array.  If none set, take default. */
 907         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 908                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 909         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 910                 synctype[nsynctypes++] = RTWS_COND_GET;
 911                 pr_info("%s: Testing conditional GPs.\n", __func__);
 912         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 913                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 914         }
 915         if (gp_exp1 && cur_ops->exp_sync) {
 916                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 917                 pr_info("%s: Testing expedited GPs.\n", __func__);
 918         } else if (gp_exp && !cur_ops->exp_sync) {
 919                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 920         }
 921         if (gp_normal1 && cur_ops->deferred_free) {
 922                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 923                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 924         } else if (gp_normal && !cur_ops->deferred_free) {
 925                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 926         }
 927         if (gp_sync1 && cur_ops->sync) {
 928                 synctype[nsynctypes++] = RTWS_SYNC;
 929                 pr_info("%s: Testing normal GPs.\n", __func__);
 930         } else if (gp_sync && !cur_ops->sync) {
 931                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 932         }
 933         if (WARN_ONCE(nsynctypes == 0,
 934                       "rcu_torture_writer: No update-side primitives.\n")) {
 935                 /*
 936                  * No updates primitives, so don't try updating.
 937                  * The resulting test won't be testing much, hence the
 938                  * above WARN_ONCE().
 939                  */
 940                 rcu_torture_writer_state = RTWS_STOPPING;
 941                 torture_kthread_stopping("rcu_torture_writer");
 942         }
 943
 944         do {
 945                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 946                 schedule_timeout_uninterruptible(1);
 947                 rp = rcu_torture_alloc();
 948                 if (rp == NULL)
 949                         continue;
 950                 rp->rtort_pipe_count = 0;
 951                 rcu_torture_writer_state = RTWS_DELAY;
 952                 udelay(torture_random(&rand) & 0x3ff);
 953                 rcu_torture_writer_state = RTWS_REPLACE;
 954                 old_rp = rcu_dereference_check(rcu_torture_current,
 955                                                current == writer_task);
 956                 rp->rtort_mbtest = 1;
 957                 rcu_assign_pointer(rcu_torture_current, rp);
 958                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 959                 if (old_rp) {
 960                         i = old_rp->rtort_pipe_count;
 961                         if (i > RCU_TORTURE_PIPE_LEN)
 962                                 i = RCU_TORTURE_PIPE_LEN;
 963                         atomic_inc(&rcu_torture_wcount[i]);
 964                         old_rp->rtort_pipe_count++;
 965                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 966                         case RTWS_DEF_FREE:
 967                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 968                                 cur_ops->deferred_free(old_rp);
 969                                 break;
 970                         case RTWS_EXP_SYNC:
 971                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 972                                 cur_ops->exp_sync();
 973                                 rcu_torture_pipe_update(old_rp);
 974                                 break;
 975                         case RTWS_COND_GET:
 976                                 rcu_torture_writer_state = RTWS_COND_GET;
 977                                 gp_snap = cur_ops->get_state();
 978                                 i = torture_random(&rand) % 16;
 979                                 if (i != 0)
 980                                         schedule_timeout_interruptible(i);
 981                                 udelay(torture_random(&rand) % 1000);
 982                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 983                                 cur_ops->cond_sync(gp_snap);
 984                                 rcu_torture_pipe_update(old_rp);
 985                                 break;
 986                         case RTWS_SYNC:
 987                                 rcu_torture_writer_state = RTWS_SYNC;
 988                                 cur_ops->sync();
 989                                 rcu_torture_pipe_update(old_rp);
 990                                 break;
 991                         default:
 992                                 WARN_ON_ONCE(1);
 993                                 break;
 994                         }
 995                 }
 996                 WRITE_ONCE(rcu_torture_current_version,
 997                            rcu_torture_current_version + 1);
 998                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
 999                 if (can_expedite &&
1000                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1001                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1002                         if (expediting >= 0)
1003                                 rcu_expedite_gp();
1004                         else
1005                                 rcu_unexpedite_gp();
1006                         if (++expediting > 3)
1007                                 expediting = -expediting;
1008                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1009                         can_expedite = !rcu_gp_is_expedited() &&
1010                                        !rcu_gp_is_normal();
1011                 }
1012                 rcu_torture_writer_state = RTWS_STUTTER;
1013                 if (stutter_wait("rcu_torture_writer"))
1014                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1015                                 if (list_empty(&rcu_tortures[i].rtort_free))
1016                                         WARN_ON_ONCE(1);
1017         } while (!torture_must_stop());
1018         /* Reset expediting back to unexpedited. */
1019         if (expediting > 0)
1020                 expediting = -expediting;
1021         while (can_expedite && expediting++ < 0)
1022                 rcu_unexpedite_gp();
1023         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1024         if (!can_expedite)
1025                 pr_alert("%s" TORTURE_FLAG
1026                          " Dynamic grace-period expediting was disabled.\n",
1027                          torture_type);
1028         rcu_torture_writer_state = RTWS_STOPPING;
1029         torture_kthread_stopping("rcu_torture_writer");
1030         return 0;
1031 }
1032
1033 /*
1034  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1035  * delay between calls.
1036  */
1037 static int
1038 rcu_torture_fakewriter(void *arg)
1039 {
1040         DEFINE_TORTURE_RANDOM(rand);
1041
1042         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1043         set_user_nice(current, MAX_NICE);
1044
1045         do {
1046                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1047                 udelay(torture_random(&rand) & 0x3ff);
1048                 if (cur_ops->cb_barrier != NULL &&
1049                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1050                         cur_ops->cb_barrier();
1051                 } else if (gp_normal == gp_exp) {
1052                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1053                                 cur_ops->sync();
1054                         else if (cur_ops->exp_sync)
1055                                 cur_ops->exp_sync();
1056                 } else if (gp_normal && cur_ops->sync) {
1057                         cur_ops->sync();
1058                 } else if (cur_ops->exp_sync) {
1059                         cur_ops->exp_sync();
1060                 }
1061                 stutter_wait("rcu_torture_fakewriter");
1062         } while (!torture_must_stop());
1063
1064         torture_kthread_stopping("rcu_torture_fakewriter");
1065         return 0;
1066 }
1067
1068 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1069 {
1070         kfree(rhp);
1071 }
1072
1073 /*
1074  * Do one extension of an RCU read-side critical section using the
1075  * current reader state in readstate (set to zero for initial entry
1076  * to extended critical section), set the new state as specified by
1077  * newstate (set to zero for final exit from extended critical section),
1078  * and random-number-generator state in trsp.  If this is neither the
1079  * beginning or end of the critical section and if there was actually a
1080  * change, do a ->read_delay().
1081  */
1082 static void rcutorture_one_extend(int *readstate, int newstate,
1083                                   struct torture_random_state *trsp,
1084                                   struct rt_read_seg *rtrsp)
1085 {
1086         int idxnew = -1;
1087         int idxold = *readstate;
1088         int statesnew = ~*readstate & newstate;
1089         int statesold = *readstate & ~newstate;
1090
1091         WARN_ON_ONCE(idxold < 0);
1092         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1093         rtrsp->rt_readstate = newstate;
1094
1095         /* First, put new protection in place to avoid critical-section gap. */
1096         if (statesnew & RCUTORTURE_RDR_BH)
1097                 local_bh_disable();
1098         if (statesnew & RCUTORTURE_RDR_IRQ)
1099                 local_irq_disable();
1100         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1101                 preempt_disable();
1102         if (statesnew & RCUTORTURE_RDR_RBH)
1103                 rcu_read_lock_bh();
1104         if (statesnew & RCUTORTURE_RDR_SCHED)
1105                 rcu_read_lock_sched();
1106         if (statesnew & RCUTORTURE_RDR_RCU)
1107                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1108
1109         /* Next, remove old protection, irq first due to bh conflict. */
1110         if (statesold & RCUTORTURE_RDR_IRQ)
1111                 local_irq_enable();
1112         if (statesold & RCUTORTURE_RDR_BH)
1113                 local_bh_enable();
1114         if (statesold & RCUTORTURE_RDR_PREEMPT)
1115                 preempt_enable();
1116         if (statesold & RCUTORTURE_RDR_RBH)
1117                 rcu_read_unlock_bh();
1118         if (statesold & RCUTORTURE_RDR_SCHED)
1119                 rcu_read_unlock_sched();
1120         if (statesold & RCUTORTURE_RDR_RCU)
1121                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1122
1123         /* Delay if neither beginning nor end and there was a change. */
1124         if ((statesnew || statesold) && *readstate && newstate)
1125                 cur_ops->read_delay(trsp, rtrsp);
1126
1127         /* Update the reader state. */
1128         if (idxnew == -1)
1129                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1130         WARN_ON_ONCE(idxnew < 0);
1131         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1132         *readstate = idxnew | newstate;
1133         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1134         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1135 }
1136
1137 /* Return the biggest extendables mask given current RCU and boot parameters. */
1138 static int rcutorture_extend_mask_max(void)
1139 {
1140         int mask;
1141
1142         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1143         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1144         mask = mask | RCUTORTURE_RDR_RCU;
1145         return mask;
1146 }
1147
1148 /* Return a random protection state mask, but with at least one bit set. */
1149 static int
1150 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1151 {
1152         int mask = rcutorture_extend_mask_max();
1153         unsigned long randmask1 = torture_random(trsp) >> 8;
1154         unsigned long randmask2 = randmask1 >> 3;
1155
1156         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1157         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1158         if (!(randmask1 & 0x7))
1159                 mask = mask & randmask2;
1160         else
1161                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1162         /* Can't enable bh w/irq disabled. */
1163         if ((mask & RCUTORTURE_RDR_IRQ) &&
1164             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1165              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1166                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1167         return mask ?: RCUTORTURE_RDR_RCU;
1168 }
1169
1170 /*
1171  * Do a randomly selected number of extensions of an existing RCU read-side
1172  * critical section.
1173  */
1174 static struct rt_read_seg *
1175 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1176                        struct rt_read_seg *rtrsp)
1177 {
1178         int i;
1179         int j;
1180         int mask = rcutorture_extend_mask_max();
1181
1182         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1183         if (!((mask - 1) & mask))
1184                 return rtrsp;  /* Current RCU reader not extendable. */
1185         /* Bias towards larger numbers of loops. */
1186         i = (torture_random(trsp) >> 3);
1187         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1188         for (j = 0; j < i; j++) {
1189                 mask = rcutorture_extend_mask(*readstate, trsp);
1190                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1191         }
1192         return &rtrsp[j];
1193 }
1194
1195 /*
1196  * Do one read-side critical section, returning false if there was
1197  * no data to read.  Can be invoked both from process context and
1198  * from a timer handler.
1199  */
1200 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1201 {
1202         int i;
1203         unsigned long started;
1204         unsigned long completed;
1205         int newstate;
1206         struct rcu_torture *p;
1207         int pipe_count;
1208         int readstate = 0;
1209         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1210         struct rt_read_seg *rtrsp = &rtseg[0];
1211         struct rt_read_seg *rtrsp1;
1212         unsigned long long ts;
1213
1214         newstate = rcutorture_extend_mask(readstate, trsp);
1215         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1216         started = cur_ops->get_gp_seq();
1217         ts = rcu_trace_clock_local();
1218         p = rcu_dereference_check(rcu_torture_current,
1219                                   rcu_read_lock_bh_held() ||
1220                                   rcu_read_lock_sched_held() ||
1221                                   srcu_read_lock_held(srcu_ctlp) ||
1222                                   torturing_tasks());
1223         if (p == NULL) {
1224                 /* Wait for rcu_torture_writer to get underway */
1225                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1226                 return false;
1227         }
1228         if (p->rtort_mbtest == 0)
1229                 atomic_inc(&n_rcu_torture_mberror);
1230         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1231         preempt_disable();
1232         pipe_count = p->rtort_pipe_count;
1233         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1234                 /* Should not happen, but... */
1235                 pipe_count = RCU_TORTURE_PIPE_LEN;
1236         }
1237         completed = cur_ops->get_gp_seq();
1238         if (pipe_count > 1) {
1239                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1240                                           ts, started, completed);
1241                 rcu_ftrace_dump(DUMP_ALL);
1242         }
1243         __this_cpu_inc(rcu_torture_count[pipe_count]);
1244         completed = rcutorture_seq_diff(completed, started);
1245         if (completed > RCU_TORTURE_PIPE_LEN) {
1246                 /* Should not happen, but... */
1247                 completed = RCU_TORTURE_PIPE_LEN;
1248         }
1249         __this_cpu_inc(rcu_torture_batch[completed]);
1250         preempt_enable();
1251         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1252         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1253
1254         /* If error or close call, record the sequence of reader protections. */
1255         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1256                 i = 0;
1257                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1258                         err_segs[i++] = *rtrsp1;
1259                 rt_read_nsegs = i;
1260         }
1261
1262         return true;
1263 }
1264
1265 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1266
1267 /*
1268  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1269  * incrementing the corresponding element of the pipeline array.  The
1270  * counter in the element should never be greater than 1, otherwise, the
1271  * RCU implementation is broken.
1272  */
1273 static void rcu_torture_timer(struct timer_list *unused)
1274 {
1275         atomic_long_inc(&n_rcu_torture_timers);
1276         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1277
1278         /* Test call_rcu() invocation from interrupt handler. */
1279         if (cur_ops->call) {
1280                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1281
1282                 if (rhp)
1283                         cur_ops->call(rhp, rcu_torture_timer_cb);
1284         }
1285 }
1286
1287 /*
1288  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1289  * incrementing the corresponding element of the pipeline array.  The
1290  * counter in the element should never be greater than 1, otherwise, the
1291  * RCU implementation is broken.
1292  */
1293 static int
1294 rcu_torture_reader(void *arg)
1295 {
1296         unsigned long lastsleep = jiffies;
1297         long myid = (long)arg;
1298         int mynumonline = myid;
1299         DEFINE_TORTURE_RANDOM(rand);
1300         struct timer_list t;
1301
1302         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1303         set_user_nice(current, MAX_NICE);
1304         if (irqreader && cur_ops->irq_capable)
1305                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1306
1307         do {
1308                 if (irqreader && cur_ops->irq_capable) {
1309                         if (!timer_pending(&t))
1310                                 mod_timer(&t, jiffies + 1);
1311                 }
1312                 if (!rcu_torture_one_read(&rand))
1313                         schedule_timeout_interruptible(HZ);
1314                 if (time_after(jiffies, lastsleep)) {
1315                         schedule_timeout_interruptible(1);
1316                         lastsleep = jiffies + 10;
1317                 }
1318                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1319                         schedule_timeout_interruptible(HZ / 5);
1320                 stutter_wait("rcu_torture_reader");
1321         } while (!torture_must_stop());
1322         if (irqreader && cur_ops->irq_capable) {
1323                 del_timer_sync(&t);
1324                 destroy_timer_on_stack(&t);
1325         }
1326         torture_kthread_stopping("rcu_torture_reader");
1327         return 0;
1328 }
1329
1330 /*
1331  * Print torture statistics.  Caller must ensure that there is only
1332  * one call to this function at a given time!!!  This is normally
1333  * accomplished by relying on the module system to only have one copy
1334  * of the module loaded, and then by giving the rcu_torture_stats
1335  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1336  * thread is not running).
1337  */
1338 static void
1339 rcu_torture_stats_print(void)
1340 {
1341         int cpu;
1342         int i;
1343         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1344         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1345         static unsigned long rtcv_snap = ULONG_MAX;
1346         static bool splatted;
1347         struct task_struct *wtp;
1348
1349         for_each_possible_cpu(cpu) {
1350                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1351                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1352                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1353                 }
1354         }
1355         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1356                 if (pipesummary[i] != 0)
1357                         break;
1358         }
1359
1360         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1361         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1362                 rcu_torture_current,
1363                 rcu_torture_current_version,
1364                 list_empty(&rcu_torture_freelist),
1365                 atomic_read(&n_rcu_torture_alloc),
1366                 atomic_read(&n_rcu_torture_alloc_fail),
1367                 atomic_read(&n_rcu_torture_free));
1368         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1369                 atomic_read(&n_rcu_torture_mberror),
1370                 n_rcu_torture_barrier_error,
1371                 n_rcu_torture_boost_ktrerror,
1372                 n_rcu_torture_boost_rterror);
1373         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1374                 n_rcu_torture_boost_failure,
1375                 n_rcu_torture_boosts,
1376                 atomic_long_read(&n_rcu_torture_timers));
1377         torture_onoff_stats();
1378         pr_cont("barrier: %ld/%ld:%ld\n",
1379                 n_barrier_successes,
1380                 n_barrier_attempts,
1381                 n_rcu_torture_barrier_error);
1382
1383         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1384         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1385             n_rcu_torture_barrier_error != 0 ||
1386             n_rcu_torture_boost_ktrerror != 0 ||
1387             n_rcu_torture_boost_rterror != 0 ||
1388             n_rcu_torture_boost_failure != 0 ||
1389             i > 1) {
1390                 pr_cont("%s", "!!! ");
1391                 atomic_inc(&n_rcu_torture_error);
1392                 WARN_ON_ONCE(1);
1393         }
1394         pr_cont("Reader Pipe: ");
1395         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1396                 pr_cont(" %ld", pipesummary[i]);
1397         pr_cont("\n");
1398
1399         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1400         pr_cont("Reader Batch: ");
1401         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1402                 pr_cont(" %ld", batchsummary[i]);
1403         pr_cont("\n");
1404
1405         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1406         pr_cont("Free-Block Circulation: ");
1407         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1408                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1409         }
1410         pr_cont("\n");
1411
1412         if (cur_ops->stats)
1413                 cur_ops->stats();
1414         if (rtcv_snap == rcu_torture_current_version &&
1415             rcu_torture_current != NULL) {
1416                 int __maybe_unused flags = 0;
1417                 unsigned long __maybe_unused gp_seq = 0;
1418
1419                 rcutorture_get_gp_data(cur_ops->ttype,
1420                                        &flags, &gp_seq);
1421                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1422                                         &flags, &gp_seq);
1423                 wtp = READ_ONCE(writer_task);
1424                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1425                          rcu_torture_writer_state_getname(),
1426                          rcu_torture_writer_state, gp_seq, flags,
1427                          wtp == NULL ? ~0UL : wtp->state,
1428                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1429                 if (!splatted && wtp) {
1430                         sched_show_task(wtp);
1431                         splatted = true;
1432                 }
1433                 show_rcu_gp_kthreads();
1434                 rcu_ftrace_dump(DUMP_ALL);
1435         }
1436         rtcv_snap = rcu_torture_current_version;
1437 }
1438
1439 /*
1440  * Periodically prints torture statistics, if periodic statistics printing
1441  * was specified via the stat_interval module parameter.
1442  */
1443 static int
1444 rcu_torture_stats(void *arg)
1445 {
1446         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1447         do {
1448                 schedule_timeout_interruptible(stat_interval * HZ);
1449                 rcu_torture_stats_print();
1450                 torture_shutdown_absorb("rcu_torture_stats");
1451         } while (!torture_must_stop());
1452         torture_kthread_stopping("rcu_torture_stats");
1453         return 0;
1454 }
1455
1456 static void
1457 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1458 {
1459         pr_alert("%s" TORTURE_FLAG
1460                  "--- %s: nreaders=%d nfakewriters=%d "
1461                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1462                  "shuffle_interval=%d stutter=%d irqreader=%d "
1463                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1464                  "test_boost=%d/%d test_boost_interval=%d "
1465                  "test_boost_duration=%d shutdown_secs=%d "
1466                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1467                  "n_barrier_cbs=%d "
1468                  "onoff_interval=%d onoff_holdoff=%d\n",
1469                  torture_type, tag, nrealreaders, nfakewriters,
1470                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1471                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1472                  test_boost, cur_ops->can_boost,
1473                  test_boost_interval, test_boost_duration, shutdown_secs,
1474                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1475                  n_barrier_cbs,
1476                  onoff_interval, onoff_holdoff);
1477 }
1478
1479 static int rcutorture_booster_cleanup(unsigned int cpu)
1480 {
1481         struct task_struct *t;
1482
1483         if (boost_tasks[cpu] == NULL)
1484                 return 0;
1485         mutex_lock(&boost_mutex);
1486         t = boost_tasks[cpu];
1487         boost_tasks[cpu] = NULL;
1488         rcu_torture_enable_rt_throttle();
1489         mutex_unlock(&boost_mutex);
1490
1491         /* This must be outside of the mutex, otherwise deadlock! */
1492         torture_stop_kthread(rcu_torture_boost, t);
1493         return 0;
1494 }
1495
1496 static int rcutorture_booster_init(unsigned int cpu)
1497 {
1498         int retval;
1499
1500         if (boost_tasks[cpu] != NULL)
1501                 return 0;  /* Already created, nothing more to do. */
1502
1503         /* Don't allow time recalculation while creating a new task. */
1504         mutex_lock(&boost_mutex);
1505         rcu_torture_disable_rt_throttle();
1506         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1507         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1508                                                   cpu_to_node(cpu),
1509                                                   "rcu_torture_boost");
1510         if (IS_ERR(boost_tasks[cpu])) {
1511                 retval = PTR_ERR(boost_tasks[cpu]);
1512                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1513                 n_rcu_torture_boost_ktrerror++;
1514                 boost_tasks[cpu] = NULL;
1515                 mutex_unlock(&boost_mutex);
1516                 return retval;
1517         }
1518         kthread_bind(boost_tasks[cpu], cpu);
1519         wake_up_process(boost_tasks[cpu]);
1520         mutex_unlock(&boost_mutex);
1521         return 0;
1522 }
1523
1524 /*
1525  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1526  * induces a CPU stall for the time specified by stall_cpu.
1527  */
1528 static int rcu_torture_stall(void *args)
1529 {
1530         unsigned long stop_at;
1531
1532         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1533         if (stall_cpu_holdoff > 0) {
1534                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1535                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1536                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1537         }
1538         if (!kthread_should_stop()) {
1539                 stop_at = ktime_get_seconds() + stall_cpu;
1540                 /* RCU CPU stall is expected behavior in following code. */
1541                 rcu_read_lock();
1542                 if (stall_cpu_irqsoff)
1543                         local_irq_disable();
1544                 else
1545                         preempt_disable();
1546                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1547                          smp_processor_id());
1548                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1549                                     stop_at))
1550                         continue;  /* Induce RCU CPU stall warning. */
1551                 if (stall_cpu_irqsoff)
1552                         local_irq_enable();
1553                 else
1554                         preempt_enable();
1555                 rcu_read_unlock();
1556                 pr_alert("rcu_torture_stall end.\n");
1557         }
1558         torture_shutdown_absorb("rcu_torture_stall");
1559         while (!kthread_should_stop())
1560                 schedule_timeout_interruptible(10 * HZ);
1561         return 0;
1562 }
1563
1564 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1565 static int __init rcu_torture_stall_init(void)
1566 {
1567         if (stall_cpu <= 0)
1568                 return 0;
1569         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1570 }
1571
1572 /* State structure for forward-progress self-propagating RCU callback. */
1573 struct fwd_cb_state {
1574         struct rcu_head rh;
1575         int stop;
1576 };
1577
1578 /*
1579  * Forward-progress self-propagating RCU callback function.  Because
1580  * callbacks run from softirq, this function is an implicit RCU read-side
1581  * critical section.
1582  */
1583 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1584 {
1585         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1586
1587         if (READ_ONCE(fcsp->stop)) {
1588                 WRITE_ONCE(fcsp->stop, 2);
1589                 return;
1590         }
1591         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1592 }
1593
1594 /* State for continuous-flood RCU callbacks. */
1595 struct rcu_fwd_cb {
1596         struct rcu_head rh;
1597         struct rcu_fwd_cb *rfc_next;
1598         int rfc_gps;
1599 };
1600 static DEFINE_SPINLOCK(rcu_fwd_lock);
1601 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1602 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1603 static long n_launders_cb;
1604 static unsigned long rcu_fwd_startat;
1605 static bool rcu_fwd_emergency_stop;
1606 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1607 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1608 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1609 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1610 struct rcu_launder_hist {
1611         long n_launders;
1612         unsigned long launder_gp_seq;
1613 };
1614 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1615 static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1616 static unsigned long rcu_launder_gp_seq_start;
1617
1618 static void rcu_torture_fwd_cb_hist(void)
1619 {
1620         unsigned long gps;
1621         unsigned long gps_old;
1622         int i;
1623         int j;
1624
1625         for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1626                 if (n_launders_hist[i].n_launders > 0)
1627                         break;
1628         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1629                  __func__, jiffies - rcu_fwd_startat);
1630         gps_old = rcu_launder_gp_seq_start;
1631         for (j = 0; j <= i; j++) {
1632                 gps = n_launders_hist[j].launder_gp_seq;
1633                 pr_cont(" %ds/%d: %ld:%ld",
1634                         j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1635                         rcutorture_seq_diff(gps, gps_old));
1636                 gps_old = gps;
1637         }
1638         pr_cont("\n");
1639 }
1640
1641 /* Callback function for continuous-flood RCU callbacks. */
1642 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1643 {
1644         unsigned long flags;
1645         int i;
1646         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1647         struct rcu_fwd_cb **rfcpp;
1648
1649         rfcp->rfc_next = NULL;
1650         rfcp->rfc_gps++;
1651         spin_lock_irqsave(&rcu_fwd_lock, flags);
1652         rfcpp = rcu_fwd_cb_tail;
1653         rcu_fwd_cb_tail = &rfcp->rfc_next;
1654         WRITE_ONCE(*rfcpp, rfcp);
1655         WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1656         i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1657         if (i >= ARRAY_SIZE(n_launders_hist))
1658                 i = ARRAY_SIZE(n_launders_hist) - 1;
1659         n_launders_hist[i].n_launders++;
1660         n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1661         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1662 }
1663
1664 /*
1665  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1666  * test is over or because we hit an OOM event.
1667  */
1668 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1669 {
1670         unsigned long flags;
1671         unsigned long freed = 0;
1672         struct rcu_fwd_cb *rfcp;
1673
1674         for (;;) {
1675                 spin_lock_irqsave(&rcu_fwd_lock, flags);
1676                 rfcp = rcu_fwd_cb_head;
1677                 if (!rfcp)
1678                         break;
1679                 rcu_fwd_cb_head = rfcp->rfc_next;
1680                 if (!rcu_fwd_cb_head)
1681                         rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1682                 spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1683                 kfree(rfcp);
1684                 freed++;
1685         }
1686         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1687         return freed;
1688 }
1689
1690 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1691 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1692 {
1693         unsigned long cver;
1694         unsigned long dur;
1695         struct fwd_cb_state fcs;
1696         unsigned long gps;
1697         int idx;
1698         int sd;
1699         int sd4;
1700         bool selfpropcb = false;
1701         unsigned long stopat;
1702         static DEFINE_TORTURE_RANDOM(trs);
1703
1704         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1705                 init_rcu_head_on_stack(&fcs.rh);
1706                 selfpropcb = true;
1707         }
1708
1709         /* Tight loop containing cond_resched(). */
1710         if  (selfpropcb) {
1711                 WRITE_ONCE(fcs.stop, 0);
1712                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1713         }
1714         cver = READ_ONCE(rcu_torture_current_version);
1715         gps = cur_ops->get_gp_seq();
1716         sd = cur_ops->stall_dur() + 1;
1717         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1718         dur = sd4 + torture_random(&trs) % (sd - sd4);
1719         WRITE_ONCE(rcu_fwd_startat, jiffies);
1720         stopat = rcu_fwd_startat + dur;
1721         while (time_before(jiffies, stopat) &&
1722                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1723                 idx = cur_ops->readlock();
1724                 udelay(10);
1725                 cur_ops->readunlock(idx);
1726                 if (!fwd_progress_need_resched || need_resched())
1727                         cond_resched();
1728         }
1729         (*tested_tries)++;
1730         if (!time_before(jiffies, stopat) &&
1731             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1732                 (*tested)++;
1733                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1734                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1735                 WARN_ON(!cver && gps < 2);
1736                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1737         }
1738         if (selfpropcb) {
1739                 WRITE_ONCE(fcs.stop, 1);
1740                 cur_ops->sync(); /* Wait for running CB to complete. */
1741                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1742         }
1743
1744         if (selfpropcb) {
1745                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1746                 destroy_rcu_head_on_stack(&fcs.rh);
1747         }
1748 }
1749
1750 /* Carry out call_rcu() forward-progress testing. */
1751 static void rcu_torture_fwd_prog_cr(void)
1752 {
1753         unsigned long cver;
1754         unsigned long gps;
1755         int i;
1756         long n_launders;
1757         long n_launders_cb_snap;
1758         long n_launders_sa;
1759         long n_max_cbs;
1760         long n_max_gps;
1761         struct rcu_fwd_cb *rfcp;
1762         struct rcu_fwd_cb *rfcpn;
1763         unsigned long stopat;
1764         unsigned long stoppedat;
1765
1766         if (READ_ONCE(rcu_fwd_emergency_stop))
1767                 return; /* Get out of the way quickly, no GP wait! */
1768
1769         /* Loop continuously posting RCU callbacks. */
1770         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1771         cur_ops->sync(); /* Later readers see above write. */
1772         WRITE_ONCE(rcu_fwd_startat, jiffies);
1773         stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1774         n_launders = 0;
1775         n_launders_cb = 0;
1776         n_launders_sa = 0;
1777         n_max_cbs = 0;
1778         n_max_gps = 0;
1779         for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1780                 n_launders_hist[i].n_launders = 0;
1781         cver = READ_ONCE(rcu_torture_current_version);
1782         gps = cur_ops->get_gp_seq();
1783         rcu_launder_gp_seq_start = gps;
1784         while (time_before(jiffies, stopat) &&
1785                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1786                 rfcp = READ_ONCE(rcu_fwd_cb_head);
1787                 rfcpn = NULL;
1788                 if (rfcp)
1789                         rfcpn = READ_ONCE(rfcp->rfc_next);
1790                 if (rfcpn) {
1791                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1792                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1793                                 break;
1794                         rcu_fwd_cb_head = rfcpn;
1795                         n_launders++;
1796                         n_launders_sa++;
1797                 } else {
1798                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1799                         if (WARN_ON_ONCE(!rfcp)) {
1800                                 schedule_timeout_interruptible(1);
1801                                 continue;
1802                         }
1803                         n_max_cbs++;
1804                         n_launders_sa = 0;
1805                         rfcp->rfc_gps = 0;
1806                 }
1807                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1808                 cond_resched();
1809         }
1810         stoppedat = jiffies;
1811         n_launders_cb_snap = READ_ONCE(n_launders_cb);
1812         cver = READ_ONCE(rcu_torture_current_version) - cver;
1813         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1814         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1815         (void)rcu_torture_fwd_prog_cbfree();
1816
1817         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1818         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
1819                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1820                 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",
1821                          __func__,
1822                          stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1823                          n_launders + n_max_cbs - n_launders_cb_snap,
1824                          n_launders, n_launders_sa,
1825                          n_max_gps, n_max_cbs, cver, gps);
1826                 rcu_torture_fwd_cb_hist();
1827         }
1828 }
1829
1830
1831 /*
1832  * OOM notifier, but this only prints diagnostic information for the
1833  * current forward-progress test.
1834  */
1835 static int rcutorture_oom_notify(struct notifier_block *self,
1836                                  unsigned long notused, void *nfreed)
1837 {
1838         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1839              __func__);
1840         rcu_torture_fwd_cb_hist();
1841         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
1842         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1843         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1844         pr_info("%s: Freed %lu RCU callbacks.\n",
1845                 __func__, rcu_torture_fwd_prog_cbfree());
1846         rcu_barrier();
1847         pr_info("%s: Freed %lu RCU callbacks.\n",
1848                 __func__, rcu_torture_fwd_prog_cbfree());
1849         rcu_barrier();
1850         pr_info("%s: Freed %lu RCU callbacks.\n",
1851                 __func__, rcu_torture_fwd_prog_cbfree());
1852         smp_mb(); /* Frees before return to avoid redoing OOM. */
1853         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1854         pr_info("%s returning after OOM processing.\n", __func__);
1855         return NOTIFY_OK;
1856 }
1857
1858 static struct notifier_block rcutorture_oom_nb = {
1859         .notifier_call = rcutorture_oom_notify
1860 };
1861
1862 /* Carry out grace-period forward-progress testing. */
1863 static int rcu_torture_fwd_prog(void *args)
1864 {
1865         int tested = 0;
1866         int tested_tries = 0;
1867
1868         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1869         rcu_bind_current_to_nocb();
1870         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1871                 set_user_nice(current, MAX_NICE);
1872         do {
1873                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1874                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
1875                 register_oom_notifier(&rcutorture_oom_nb);
1876                 rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1877                 rcu_torture_fwd_prog_cr();
1878                 unregister_oom_notifier(&rcutorture_oom_nb);
1879
1880                 /* Avoid slow periods, better to test when busy. */
1881                 stutter_wait("rcu_torture_fwd_prog");
1882         } while (!torture_must_stop());
1883         /* Short runs might not contain a valid forward-progress attempt. */
1884         WARN_ON(!tested && tested_tries >= 5);
1885         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1886         torture_kthread_stopping("rcu_torture_fwd_prog");
1887         return 0;
1888 }
1889
1890 /* If forward-progress checking is requested and feasible, spawn the thread. */
1891 static int __init rcu_torture_fwd_prog_init(void)
1892 {
1893         if (!fwd_progress)
1894                 return 0; /* Not requested, so don't do it. */
1895         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1896             cur_ops == &rcu_busted_ops) {
1897                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1898                 return 0;
1899         }
1900         if (stall_cpu > 0) {
1901                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1902                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1903                         return -EINVAL; /* In module, can fail back to user. */
1904                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1905                 return 0;
1906         }
1907         if (fwd_progress_holdoff <= 0)
1908                 fwd_progress_holdoff = 1;
1909         if (fwd_progress_div <= 0)
1910                 fwd_progress_div = 4;
1911         return torture_create_kthread(rcu_torture_fwd_prog,
1912                                       NULL, fwd_prog_task);
1913 }
1914
1915 /* Callback function for RCU barrier testing. */
1916 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1917 {
1918         atomic_inc(&barrier_cbs_invoked);
1919 }
1920
1921 /* kthread function to register callbacks used to test RCU barriers. */
1922 static int rcu_torture_barrier_cbs(void *arg)
1923 {
1924         long myid = (long)arg;
1925         bool lastphase = 0;
1926         bool newphase;
1927         struct rcu_head rcu;
1928
1929         init_rcu_head_on_stack(&rcu);
1930         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1931         set_user_nice(current, MAX_NICE);
1932         do {
1933                 wait_event(barrier_cbs_wq[myid],
1934                            (newphase =
1935                             smp_load_acquire(&barrier_phase)) != lastphase ||
1936                            torture_must_stop());
1937                 lastphase = newphase;
1938                 if (torture_must_stop())
1939                         break;
1940                 /*
1941                  * The above smp_load_acquire() ensures barrier_phase load
1942                  * is ordered before the following ->call().
1943                  */
1944                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1945                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1946                 local_irq_enable();
1947                 if (atomic_dec_and_test(&barrier_cbs_count))
1948                         wake_up(&barrier_wq);
1949         } while (!torture_must_stop());
1950         if (cur_ops->cb_barrier != NULL)
1951                 cur_ops->cb_barrier();
1952         destroy_rcu_head_on_stack(&rcu);
1953         torture_kthread_stopping("rcu_torture_barrier_cbs");
1954         return 0;
1955 }
1956
1957 /* kthread function to drive and coordinate RCU barrier testing. */
1958 static int rcu_torture_barrier(void *arg)
1959 {
1960         int i;
1961
1962         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1963         do {
1964                 atomic_set(&barrier_cbs_invoked, 0);
1965                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1966                 /* Ensure barrier_phase ordered after prior assignments. */
1967                 smp_store_release(&barrier_phase, !barrier_phase);
1968                 for (i = 0; i < n_barrier_cbs; i++)
1969                         wake_up(&barrier_cbs_wq[i]);
1970                 wait_event(barrier_wq,
1971                            atomic_read(&barrier_cbs_count) == 0 ||
1972                            torture_must_stop());
1973                 if (torture_must_stop())
1974                         break;
1975                 n_barrier_attempts++;
1976                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1977                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1978                         n_rcu_torture_barrier_error++;
1979                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1980                                atomic_read(&barrier_cbs_invoked),
1981                                n_barrier_cbs);
1982                         WARN_ON_ONCE(1);
1983                 } else {
1984                         n_barrier_successes++;
1985                 }
1986                 schedule_timeout_interruptible(HZ / 10);
1987         } while (!torture_must_stop());
1988         torture_kthread_stopping("rcu_torture_barrier");
1989         return 0;
1990 }
1991
1992 /* Initialize RCU barrier testing. */
1993 static int rcu_torture_barrier_init(void)
1994 {
1995         int i;
1996         int ret;
1997
1998         if (n_barrier_cbs <= 0)
1999                 return 0;
2000         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2001                 pr_alert("%s" TORTURE_FLAG
2002                          " Call or barrier ops missing for %s,\n",
2003                          torture_type, cur_ops->name);
2004                 pr_alert("%s" TORTURE_FLAG
2005                          " RCU barrier testing omitted from run.\n",
2006                          torture_type);
2007                 return 0;
2008         }
2009         atomic_set(&barrier_cbs_count, 0);
2010         atomic_set(&barrier_cbs_invoked, 0);
2011         barrier_cbs_tasks =
2012                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2013                         GFP_KERNEL);
2014         barrier_cbs_wq =
2015                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2016         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2017                 return -ENOMEM;
2018         for (i = 0; i < n_barrier_cbs; i++) {
2019                 init_waitqueue_head(&barrier_cbs_wq[i]);
2020                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2021                                              (void *)(long)i,
2022                                              barrier_cbs_tasks[i]);
2023                 if (ret)
2024                         return ret;
2025         }
2026         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2027 }
2028
2029 /* Clean up after RCU barrier testing. */
2030 static void rcu_torture_barrier_cleanup(void)
2031 {
2032         int i;
2033
2034         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2035         if (barrier_cbs_tasks != NULL) {
2036                 for (i = 0; i < n_barrier_cbs; i++)
2037                         torture_stop_kthread(rcu_torture_barrier_cbs,
2038                                              barrier_cbs_tasks[i]);
2039                 kfree(barrier_cbs_tasks);
2040                 barrier_cbs_tasks = NULL;
2041         }
2042         if (barrier_cbs_wq != NULL) {
2043                 kfree(barrier_cbs_wq);
2044                 barrier_cbs_wq = NULL;
2045         }
2046 }
2047
2048 static bool rcu_torture_can_boost(void)
2049 {
2050         static int boost_warn_once;
2051         int prio;
2052
2053         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2054                 return false;
2055
2056         prio = rcu_get_gp_kthreads_prio();
2057         if (!prio)
2058                 return false;
2059
2060         if (prio < 2) {
2061                 if (boost_warn_once  == 1)
2062                         return false;
2063
2064                 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);
2065                 boost_warn_once = 1;
2066                 return false;
2067         }
2068
2069         return true;
2070 }
2071
2072 static enum cpuhp_state rcutor_hp;
2073
2074 static void
2075 rcu_torture_cleanup(void)
2076 {
2077         int firsttime;
2078         int flags = 0;
2079         unsigned long gp_seq = 0;
2080         int i;
2081
2082         if (torture_cleanup_begin()) {
2083                 if (cur_ops->cb_barrier != NULL)
2084                         cur_ops->cb_barrier();
2085                 return;
2086         }
2087         if (!cur_ops) {
2088                 torture_cleanup_end();
2089                 return;
2090         }
2091
2092         rcu_torture_barrier_cleanup();
2093         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2094         torture_stop_kthread(rcu_torture_stall, stall_task);
2095         torture_stop_kthread(rcu_torture_writer, writer_task);
2096
2097         if (reader_tasks) {
2098                 for (i = 0; i < nrealreaders; i++)
2099                         torture_stop_kthread(rcu_torture_reader,
2100                                              reader_tasks[i]);
2101                 kfree(reader_tasks);
2102         }
2103         rcu_torture_current = NULL;
2104
2105         if (fakewriter_tasks) {
2106                 for (i = 0; i < nfakewriters; i++) {
2107                         torture_stop_kthread(rcu_torture_fakewriter,
2108                                              fakewriter_tasks[i]);
2109                 }
2110                 kfree(fakewriter_tasks);
2111                 fakewriter_tasks = NULL;
2112         }
2113
2114         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2115         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2116         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2117                  cur_ops->name, gp_seq, flags);
2118         torture_stop_kthread(rcu_torture_stats, stats_task);
2119         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2120         if (rcu_torture_can_boost())
2121                 cpuhp_remove_state(rcutor_hp);
2122
2123         /*
2124          * Wait for all RCU callbacks to fire, then do torture-type-specific
2125          * cleanup operations.
2126          */
2127         if (cur_ops->cb_barrier != NULL)
2128                 cur_ops->cb_barrier();
2129         if (cur_ops->cleanup != NULL)
2130                 cur_ops->cleanup();
2131
2132         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2133
2134         if (err_segs_recorded) {
2135                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2136                 if (rt_read_nsegs == 0)
2137                         pr_alert("\t: No segments recorded!!!\n");
2138                 firsttime = 1;
2139                 for (i = 0; i < rt_read_nsegs; i++) {
2140                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2141                         if (err_segs[i].rt_delay_jiffies != 0) {
2142                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2143                                         err_segs[i].rt_delay_jiffies);
2144                                 firsttime = 0;
2145                         }
2146                         if (err_segs[i].rt_delay_ms != 0) {
2147                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2148                                         err_segs[i].rt_delay_ms);
2149                                 firsttime = 0;
2150                         }
2151                         if (err_segs[i].rt_delay_us != 0) {
2152                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2153                                         err_segs[i].rt_delay_us);
2154                                 firsttime = 0;
2155                         }
2156                         pr_cont("%s\n",
2157                                 err_segs[i].rt_preempted ? "preempted" : "");
2158
2159                 }
2160         }
2161         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2162                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2163         else if (torture_onoff_failures())
2164                 rcu_torture_print_module_parms(cur_ops,
2165                                                "End of test: RCU_HOTPLUG");
2166         else
2167                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2168         torture_cleanup_end();
2169 }
2170
2171 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2172 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2173 {
2174 }
2175
2176 static void rcu_torture_err_cb(struct rcu_head *rhp)
2177 {
2178         /*
2179          * This -might- happen due to race conditions, but is unlikely.
2180          * The scenario that leads to this happening is that the
2181          * first of the pair of duplicate callbacks is queued,
2182          * someone else starts a grace period that includes that
2183          * callback, then the second of the pair must wait for the
2184          * next grace period.  Unlikely, but can happen.  If it
2185          * does happen, the debug-objects subsystem won't have splatted.
2186          */
2187         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2188 }
2189 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2190
2191 /*
2192  * Verify that double-free causes debug-objects to complain, but only
2193  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2194  * cannot be carried out.
2195  */
2196 static void rcu_test_debug_objects(void)
2197 {
2198 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2199         struct rcu_head rh1;
2200         struct rcu_head rh2;
2201
2202         init_rcu_head_on_stack(&rh1);
2203         init_rcu_head_on_stack(&rh2);
2204         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2205
2206         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2207         preempt_disable(); /* Prevent preemption from interrupting test. */
2208         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2209         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2210         local_irq_disable(); /* Make it harder to start a new grace period. */
2211         call_rcu(&rh2, rcu_torture_leak_cb);
2212         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2213         local_irq_enable();
2214         rcu_read_unlock();
2215         preempt_enable();
2216
2217         /* Wait for them all to get done so we can safely return. */
2218         rcu_barrier();
2219         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2220         destroy_rcu_head_on_stack(&rh1);
2221         destroy_rcu_head_on_stack(&rh2);
2222 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2223         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2224 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2225 }
2226
2227 static void rcutorture_sync(void)
2228 {
2229         static unsigned long n;
2230
2231         if (cur_ops->sync && !(++n & 0xfff))
2232                 cur_ops->sync();
2233 }
2234
2235 static int __init
2236 rcu_torture_init(void)
2237 {
2238         long i;
2239         int cpu;
2240         int firsterr = 0;
2241         static struct rcu_torture_ops *torture_ops[] = {
2242                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2243                 &busted_srcud_ops, &tasks_ops,
2244         };
2245
2246         if (!torture_init_begin(torture_type, verbose))
2247                 return -EBUSY;
2248
2249         /* Process args and tell the world that the torturer is on the job. */
2250         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2251                 cur_ops = torture_ops[i];
2252                 if (strcmp(torture_type, cur_ops->name) == 0)
2253                         break;
2254         }
2255         if (i == ARRAY_SIZE(torture_ops)) {
2256                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2257                          torture_type);
2258                 pr_alert("rcu-torture types:");
2259                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2260                         pr_cont(" %s", torture_ops[i]->name);
2261                 pr_cont("\n");
2262                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2263                 firsterr = -EINVAL;
2264                 cur_ops = NULL;
2265                 goto unwind;
2266         }
2267         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2268                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2269                 fqs_duration = 0;
2270         }
2271         if (cur_ops->init)
2272                 cur_ops->init();
2273
2274         if (nreaders >= 0) {
2275                 nrealreaders = nreaders;
2276         } else {
2277                 nrealreaders = num_online_cpus() - 2 - nreaders;
2278                 if (nrealreaders <= 0)
2279                         nrealreaders = 1;
2280         }
2281         rcu_torture_print_module_parms(cur_ops, "Start of test");
2282
2283         /* Set up the freelist. */
2284
2285         INIT_LIST_HEAD(&rcu_torture_freelist);
2286         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2287                 rcu_tortures[i].rtort_mbtest = 0;
2288                 list_add_tail(&rcu_tortures[i].rtort_free,
2289                               &rcu_torture_freelist);
2290         }
2291
2292         /* Initialize the statistics so that each run gets its own numbers. */
2293
2294         rcu_torture_current = NULL;
2295         rcu_torture_current_version = 0;
2296         atomic_set(&n_rcu_torture_alloc, 0);
2297         atomic_set(&n_rcu_torture_alloc_fail, 0);
2298         atomic_set(&n_rcu_torture_free, 0);
2299         atomic_set(&n_rcu_torture_mberror, 0);
2300         atomic_set(&n_rcu_torture_error, 0);
2301         n_rcu_torture_barrier_error = 0;
2302         n_rcu_torture_boost_ktrerror = 0;
2303         n_rcu_torture_boost_rterror = 0;
2304         n_rcu_torture_boost_failure = 0;
2305         n_rcu_torture_boosts = 0;
2306         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2307                 atomic_set(&rcu_torture_wcount[i], 0);
2308         for_each_possible_cpu(cpu) {
2309                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2310                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2311                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2312                 }
2313         }
2314         err_segs_recorded = 0;
2315         rt_read_nsegs = 0;
2316
2317         /* Start up the kthreads. */
2318
2319         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2320                                           writer_task);
2321         if (firsterr)
2322                 goto unwind;
2323         if (nfakewriters > 0) {
2324                 fakewriter_tasks = kcalloc(nfakewriters,
2325                                            sizeof(fakewriter_tasks[0]),
2326                                            GFP_KERNEL);
2327                 if (fakewriter_tasks == NULL) {
2328                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2329                         firsterr = -ENOMEM;
2330                         goto unwind;
2331                 }
2332         }
2333         for (i = 0; i < nfakewriters; i++) {
2334                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2335                                                   NULL, fakewriter_tasks[i]);
2336                 if (firsterr)
2337                         goto unwind;
2338         }
2339         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2340                                GFP_KERNEL);
2341         if (reader_tasks == NULL) {
2342                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2343                 firsterr = -ENOMEM;
2344                 goto unwind;
2345         }
2346         for (i = 0; i < nrealreaders; i++) {
2347                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2348                                                   reader_tasks[i]);
2349                 if (firsterr)
2350                         goto unwind;
2351         }
2352         if (stat_interval > 0) {
2353                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2354                                                   stats_task);
2355                 if (firsterr)
2356                         goto unwind;
2357         }
2358         if (test_no_idle_hz && shuffle_interval > 0) {
2359                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2360                 if (firsterr)
2361                         goto unwind;
2362         }
2363         if (stutter < 0)
2364                 stutter = 0;
2365         if (stutter) {
2366                 firsterr = torture_stutter_init(stutter * HZ);
2367                 if (firsterr)
2368                         goto unwind;
2369         }
2370         if (fqs_duration < 0)
2371                 fqs_duration = 0;
2372         if (fqs_duration) {
2373                 /* Create the fqs thread */
2374                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2375                                                   fqs_task);
2376                 if (firsterr)
2377                         goto unwind;
2378         }
2379         if (test_boost_interval < 1)
2380                 test_boost_interval = 1;
2381         if (test_boost_duration < 2)
2382                 test_boost_duration = 2;
2383         if (rcu_torture_can_boost()) {
2384
2385                 boost_starttime = jiffies + test_boost_interval * HZ;
2386
2387                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2388                                              rcutorture_booster_init,
2389                                              rcutorture_booster_cleanup);
2390                 if (firsterr < 0)
2391                         goto unwind;
2392                 rcutor_hp = firsterr;
2393         }
2394         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2395         if (firsterr)
2396                 goto unwind;
2397         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2398                                       rcutorture_sync);
2399         if (firsterr)
2400                 goto unwind;
2401         firsterr = rcu_torture_stall_init();
2402         if (firsterr)
2403                 goto unwind;
2404         firsterr = rcu_torture_fwd_prog_init();
2405         if (firsterr)
2406                 goto unwind;
2407         firsterr = rcu_torture_barrier_init();
2408         if (firsterr)
2409                 goto unwind;
2410         if (object_debug)
2411                 rcu_test_debug_objects();
2412         torture_init_end();
2413         return 0;
2414
2415 unwind:
2416         torture_init_end();
2417         rcu_torture_cleanup();
2418         return firsterr;
2419 }
2420
2421 module_init(rcu_torture_init);
2422 module_exit(rcu_torture_cleanup);