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         int ext_irq_conflict;
 303         const char *name;
 304 };
 305
 306 static struct rcu_torture_ops *cur_ops;
 307
 308 /*
 309  * Definitions for rcu torture testing.
 310  */
 311
 312 static int rcu_torture_read_lock(void) __acquires(RCU)
 313 {
 314         rcu_read_lock();
 315         return 0;
 316 }
 317
 318 static void
 319 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 320 {
 321         unsigned long started;
 322         unsigned long completed;
 323         const unsigned long shortdelay_us = 200;
 324         unsigned long longdelay_ms = 300;
 325         unsigned long long ts;
 326
 327         /* We want a short delay sometimes to make a reader delay the grace
 328          * period, and we want a long delay occasionally to trigger
 329          * force_quiescent_state. */
 330
 331         if (!rcu_fwd_cb_nodelay &&
 332             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 333                 started = cur_ops->get_gp_seq();
 334                 ts = rcu_trace_clock_local();
 335                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 336                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 337                 mdelay(longdelay_ms);
 338                 rtrsp->rt_delay_ms = longdelay_ms;
 339                 completed = cur_ops->get_gp_seq();
 340                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 341                                           started, completed);
 342         }
 343         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 344                 udelay(shortdelay_us);
 345                 rtrsp->rt_delay_us = shortdelay_us;
 346         }
 347         if (!preempt_count() &&
 348             !(torture_random(rrsp) % (nrealreaders * 500))) {
 349                 torture_preempt_schedule();  /* QS only if preemptible. */
 350                 rtrsp->rt_preempted = true;
 351         }
 352 }
 353
 354 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 355 {
 356         rcu_read_unlock();
 357 }
 358
 359 /*
 360  * Update callback in the pipe.  This should be invoked after a grace period.
 361  */
 362 static bool
 363 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 364 {
 365         int i;
 366
 367         i = rp->rtort_pipe_count;
 368         if (i > RCU_TORTURE_PIPE_LEN)
 369                 i = RCU_TORTURE_PIPE_LEN;
 370         atomic_inc(&rcu_torture_wcount[i]);
 371         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 372                 rp->rtort_mbtest = 0;
 373                 return true;
 374         }
 375         return false;
 376 }
 377
 378 /*
 379  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 380  * primitives.
 381  */
 382 static void
 383 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 384 {
 385         struct rcu_torture *rp;
 386         struct rcu_torture *rp1;
 387
 388         if (old_rp)
 389                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 390         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 391                 if (rcu_torture_pipe_update_one(rp)) {
 392                         list_del(&rp->rtort_free);
 393                         rcu_torture_free(rp);
 394                 }
 395         }
 396 }
 397
 398 static void
 399 rcu_torture_cb(struct rcu_head *p)
 400 {
 401         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 402
 403         if (torture_must_stop_irq()) {
 404                 /* Test is ending, just drop callbacks on the floor. */
 405                 /* The next initialization will pick up the pieces. */
 406                 return;
 407         }
 408         if (rcu_torture_pipe_update_one(rp))
 409                 rcu_torture_free(rp);
 410         else
 411                 cur_ops->deferred_free(rp);
 412 }
 413
 414 static unsigned long rcu_no_completed(void)
 415 {
 416         return 0;
 417 }
 418
 419 static void rcu_torture_deferred_free(struct rcu_torture *p)
 420 {
 421         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 422 }
 423
 424 static void rcu_sync_torture_init(void)
 425 {
 426         INIT_LIST_HEAD(&rcu_torture_removed);
 427 }
 428
 429 static struct rcu_torture_ops rcu_ops = {
 430         .ttype          = RCU_FLAVOR,
 431         .init           = rcu_sync_torture_init,
 432         .readlock       = rcu_torture_read_lock,
 433         .read_delay     = rcu_read_delay,
 434         .readunlock     = rcu_torture_read_unlock,
 435         .get_gp_seq     = rcu_get_gp_seq,
 436         .gp_diff        = rcu_seq_diff,
 437         .deferred_free  = rcu_torture_deferred_free,
 438         .sync           = synchronize_rcu,
 439         .exp_sync       = synchronize_rcu_expedited,
 440         .get_state      = get_state_synchronize_rcu,
 441         .cond_sync      = cond_synchronize_rcu,
 442         .call           = call_rcu,
 443         .cb_barrier     = rcu_barrier,
 444         .fqs            = rcu_force_quiescent_state,
 445         .stats          = NULL,
 446         .stall_dur      = rcu_jiffies_till_stall_check,
 447         .irq_capable    = 1,
 448         .can_boost      = rcu_can_boost(),
 449         .extendables    = RCUTORTURE_MAX_EXTEND,
 450         .name           = "rcu"
 451 };
 452
 453 /*
 454  * Don't even think about trying any of these in real life!!!
 455  * The names includes "busted", and they really means it!
 456  * The only purpose of these functions is to provide a buggy RCU
 457  * implementation to make sure that rcutorture correctly emits
 458  * buggy-RCU error messages.
 459  */
 460 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 461 {
 462         /* This is a deliberate bug for testing purposes only! */
 463         rcu_torture_cb(&p->rtort_rcu);
 464 }
 465
 466 static void synchronize_rcu_busted(void)
 467 {
 468         /* This is a deliberate bug for testing purposes only! */
 469 }
 470
 471 static void
 472 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 473 {
 474         /* This is a deliberate bug for testing purposes only! */
 475         func(head);
 476 }
 477
 478 static struct rcu_torture_ops rcu_busted_ops = {
 479         .ttype          = INVALID_RCU_FLAVOR,
 480         .init           = rcu_sync_torture_init,
 481         .readlock       = rcu_torture_read_lock,
 482         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 483         .readunlock     = rcu_torture_read_unlock,
 484         .get_gp_seq     = rcu_no_completed,
 485         .deferred_free  = rcu_busted_torture_deferred_free,
 486         .sync           = synchronize_rcu_busted,
 487         .exp_sync       = synchronize_rcu_busted,
 488         .call           = call_rcu_busted,
 489         .cb_barrier     = NULL,
 490         .fqs            = NULL,
 491         .stats          = NULL,
 492         .irq_capable    = 1,
 493         .name           = "busted"
 494 };
 495
 496 /*
 497  * Definitions for srcu torture testing.
 498  */
 499
 500 DEFINE_STATIC_SRCU(srcu_ctl);
 501 static struct srcu_struct srcu_ctld;
 502 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 503
 504 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 505 {
 506         return srcu_read_lock(srcu_ctlp);
 507 }
 508
 509 static void
 510 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 511 {
 512         long delay;
 513         const long uspertick = 1000000 / HZ;
 514         const long longdelay = 10;
 515
 516         /* We want there to be long-running readers, but not all the time. */
 517
 518         delay = torture_random(rrsp) %
 519                 (nrealreaders * 2 * longdelay * uspertick);
 520         if (!delay && in_task()) {
 521                 schedule_timeout_interruptible(longdelay);
 522                 rtrsp->rt_delay_jiffies = longdelay;
 523         } else {
 524                 rcu_read_delay(rrsp, rtrsp);
 525         }
 526 }
 527
 528 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 529 {
 530         srcu_read_unlock(srcu_ctlp, idx);
 531 }
 532
 533 static unsigned long srcu_torture_completed(void)
 534 {
 535         return srcu_batches_completed(srcu_ctlp);
 536 }
 537
 538 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 539 {
 540         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 541 }
 542
 543 static void srcu_torture_synchronize(void)
 544 {
 545         synchronize_srcu(srcu_ctlp);
 546 }
 547
 548 static void srcu_torture_call(struct rcu_head *head,
 549                               rcu_callback_t func)
 550 {
 551         call_srcu(srcu_ctlp, head, func);
 552 }
 553
 554 static void srcu_torture_barrier(void)
 555 {
 556         srcu_barrier(srcu_ctlp);
 557 }
 558
 559 static void srcu_torture_stats(void)
 560 {
 561         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 562 }
 563
 564 static void srcu_torture_synchronize_expedited(void)
 565 {
 566         synchronize_srcu_expedited(srcu_ctlp);
 567 }
 568
 569 static struct rcu_torture_ops srcu_ops = {
 570         .ttype          = SRCU_FLAVOR,
 571         .init           = rcu_sync_torture_init,
 572         .readlock       = srcu_torture_read_lock,
 573         .read_delay     = srcu_read_delay,
 574         .readunlock     = srcu_torture_read_unlock,
 575         .get_gp_seq     = srcu_torture_completed,
 576         .deferred_free  = srcu_torture_deferred_free,
 577         .sync           = srcu_torture_synchronize,
 578         .exp_sync       = srcu_torture_synchronize_expedited,
 579         .call           = srcu_torture_call,
 580         .cb_barrier     = srcu_torture_barrier,
 581         .stats          = srcu_torture_stats,
 582         .irq_capable    = 1,
 583         .name           = "srcu"
 584 };
 585
 586 static void srcu_torture_init(void)
 587 {
 588         rcu_sync_torture_init();
 589         WARN_ON(init_srcu_struct(&srcu_ctld));
 590         srcu_ctlp = &srcu_ctld;
 591 }
 592
 593 static void srcu_torture_cleanup(void)
 594 {
 595         static DEFINE_TORTURE_RANDOM(rand);
 596
 597         if (torture_random(&rand) & 0x800)
 598                 cleanup_srcu_struct(&srcu_ctld);
 599         else
 600                 cleanup_srcu_struct_quiesced(&srcu_ctld);
 601         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 602 }
 603
 604 /* As above, but dynamically allocated. */
 605 static struct rcu_torture_ops srcud_ops = {
 606         .ttype          = SRCU_FLAVOR,
 607         .init           = srcu_torture_init,
 608         .cleanup        = srcu_torture_cleanup,
 609         .readlock       = srcu_torture_read_lock,
 610         .read_delay     = srcu_read_delay,
 611         .readunlock     = srcu_torture_read_unlock,
 612         .get_gp_seq     = srcu_torture_completed,
 613         .deferred_free  = srcu_torture_deferred_free,
 614         .sync           = srcu_torture_synchronize,
 615         .exp_sync       = srcu_torture_synchronize_expedited,
 616         .call           = srcu_torture_call,
 617         .cb_barrier     = srcu_torture_barrier,
 618         .stats          = srcu_torture_stats,
 619         .irq_capable    = 1,
 620         .name           = "srcud"
 621 };
 622
 623 /* As above, but broken due to inappropriate reader extension. */
 624 static struct rcu_torture_ops busted_srcud_ops = {
 625         .ttype          = SRCU_FLAVOR,
 626         .init           = srcu_torture_init,
 627         .cleanup        = srcu_torture_cleanup,
 628         .readlock       = srcu_torture_read_lock,
 629         .read_delay     = rcu_read_delay,
 630         .readunlock     = srcu_torture_read_unlock,
 631         .get_gp_seq     = srcu_torture_completed,
 632         .deferred_free  = srcu_torture_deferred_free,
 633         .sync           = srcu_torture_synchronize,
 634         .exp_sync       = srcu_torture_synchronize_expedited,
 635         .call           = srcu_torture_call,
 636         .cb_barrier     = srcu_torture_barrier,
 637         .stats          = srcu_torture_stats,
 638         .irq_capable    = 1,
 639         .extendables    = RCUTORTURE_MAX_EXTEND,
 640         .name           = "busted_srcud"
 641 };
 642
 643 /*
 644  * Definitions for RCU-tasks torture testing.
 645  */
 646
 647 static int tasks_torture_read_lock(void)
 648 {
 649         return 0;
 650 }
 651
 652 static void tasks_torture_read_unlock(int idx)
 653 {
 654 }
 655
 656 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 657 {
 658         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 659 }
 660
 661 static struct rcu_torture_ops tasks_ops = {
 662         .ttype          = RCU_TASKS_FLAVOR,
 663         .init           = rcu_sync_torture_init,
 664         .readlock       = tasks_torture_read_lock,
 665         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 666         .readunlock     = tasks_torture_read_unlock,
 667         .get_gp_seq     = rcu_no_completed,
 668         .deferred_free  = rcu_tasks_torture_deferred_free,
 669         .sync           = synchronize_rcu_tasks,
 670         .exp_sync       = synchronize_rcu_tasks,
 671         .call           = call_rcu_tasks,
 672         .cb_barrier     = rcu_barrier_tasks,
 673         .fqs            = NULL,
 674         .stats          = NULL,
 675         .irq_capable    = 1,
 676         .name           = "tasks"
 677 };
 678
 679 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 680 {
 681         if (!cur_ops->gp_diff)
 682                 return new - old;
 683         return cur_ops->gp_diff(new, old);
 684 }
 685
 686 static bool __maybe_unused torturing_tasks(void)
 687 {
 688         return cur_ops == &tasks_ops;
 689 }
 690
 691 /*
 692  * RCU torture priority-boost testing.  Runs one real-time thread per
 693  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 694  * spinning waiting for them to be invoked.  If a given callback takes
 695  * too long to be invoked, we assume that priority inversion has occurred.
 696  */
 697
 698 struct rcu_boost_inflight {
 699         struct rcu_head rcu;
 700         int inflight;
 701 };
 702
 703 static void rcu_torture_boost_cb(struct rcu_head *head)
 704 {
 705         struct rcu_boost_inflight *rbip =
 706                 container_of(head, struct rcu_boost_inflight, rcu);
 707
 708         /* Ensure RCU-core accesses precede clearing ->inflight */
 709         smp_store_release(&rbip->inflight, 0);
 710 }
 711
 712 static int old_rt_runtime = -1;
 713
 714 static void rcu_torture_disable_rt_throttle(void)
 715 {
 716         /*
 717          * Disable RT throttling so that rcutorture's boost threads don't get
 718          * throttled. Only possible if rcutorture is built-in otherwise the
 719          * user should manually do this by setting the sched_rt_period_us and
 720          * sched_rt_runtime sysctls.
 721          */
 722         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 723                 return;
 724
 725         old_rt_runtime = sysctl_sched_rt_runtime;
 726         sysctl_sched_rt_runtime = -1;
 727 }
 728
 729 static void rcu_torture_enable_rt_throttle(void)
 730 {
 731         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 732                 return;
 733
 734         sysctl_sched_rt_runtime = old_rt_runtime;
 735         old_rt_runtime = -1;
 736 }
 737
 738 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 739 {
 740         if (end - start > test_boost_duration * HZ - HZ / 2) {
 741                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 742                 n_rcu_torture_boost_failure++;
 743
 744                 return true; /* failed */
 745         }
 746
 747         return false; /* passed */
 748 }
 749
 750 static int rcu_torture_boost(void *arg)
 751 {
 752         unsigned long call_rcu_time;
 753         unsigned long endtime;
 754         unsigned long oldstarttime;
 755         struct rcu_boost_inflight rbi = { .inflight = 0 };
 756         struct sched_param sp;
 757
 758         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 759
 760         /* Set real-time priority. */
 761         sp.sched_priority = 1;
 762         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 763                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 764                 n_rcu_torture_boost_rterror++;
 765         }
 766
 767         init_rcu_head_on_stack(&rbi.rcu);
 768         /* Each pass through the following loop does one boost-test cycle. */
 769         do {
 770                 /* Track if the test failed already in this test interval? */
 771                 bool failed = false;
 772
 773                 /* Increment n_rcu_torture_boosts once per boost-test */
 774                 while (!kthread_should_stop()) {
 775                         if (mutex_trylock(&boost_mutex)) {
 776                                 n_rcu_torture_boosts++;
 777                                 mutex_unlock(&boost_mutex);
 778                                 break;
 779                         }
 780                         schedule_timeout_uninterruptible(1);
 781                 }
 782                 if (kthread_should_stop())
 783                         goto checkwait;
 784
 785                 /* Wait for the next test interval. */
 786                 oldstarttime = boost_starttime;
 787                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 788                         schedule_timeout_interruptible(oldstarttime - jiffies);
 789                         stutter_wait("rcu_torture_boost");
 790                         if (torture_must_stop())
 791                                 goto checkwait;
 792                 }
 793
 794                 /* Do one boost-test interval. */
 795                 endtime = oldstarttime + test_boost_duration * HZ;
 796                 call_rcu_time = jiffies;
 797                 while (ULONG_CMP_LT(jiffies, endtime)) {
 798                         /* If we don't have a callback in flight, post one. */
 799                         if (!smp_load_acquire(&rbi.inflight)) {
 800                                 /* RCU core before ->inflight = 1. */
 801                                 smp_store_release(&rbi.inflight, 1);
 802                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 803                                 /* Check if the boost test failed */
 804                                 failed = failed ||
 805                                          rcu_torture_boost_failed(call_rcu_time,
 806                                                                  jiffies);
 807                                 call_rcu_time = jiffies;
 808                         }
 809                         stutter_wait("rcu_torture_boost");
 810                         if (torture_must_stop())
 811                                 goto checkwait;
 812                 }
 813
 814                 /*
 815                  * If boost never happened, then inflight will always be 1, in
 816                  * this case the boost check would never happen in the above
 817                  * loop so do another one here.
 818                  */
 819                 if (!failed && smp_load_acquire(&rbi.inflight))
 820                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 821
 822                 /*
 823                  * Set the start time of the next test interval.
 824                  * Yes, this is vulnerable to long delays, but such
 825                  * delays simply cause a false negative for the next
 826                  * interval.  Besides, we are running at RT priority,
 827                  * so delays should be relatively rare.
 828                  */
 829                 while (oldstarttime == boost_starttime &&
 830                        !kthread_should_stop()) {
 831                         if (mutex_trylock(&boost_mutex)) {
 832                                 boost_starttime = jiffies +
 833                                                   test_boost_interval * HZ;
 834                                 mutex_unlock(&boost_mutex);
 835                                 break;
 836                         }
 837                         schedule_timeout_uninterruptible(1);
 838                 }
 839
 840                 /* Go do the stutter. */
 841 checkwait:      stutter_wait("rcu_torture_boost");
 842         } while (!torture_must_stop());
 843
 844         /* Clean up and exit. */
 845         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 846                 torture_shutdown_absorb("rcu_torture_boost");
 847                 schedule_timeout_uninterruptible(1);
 848         }
 849         destroy_rcu_head_on_stack(&rbi.rcu);
 850         torture_kthread_stopping("rcu_torture_boost");
 851         return 0;
 852 }
 853
 854 /*
 855  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 856  * bursts of calls to force_quiescent_state(), increasing the probability
 857  * of occurrence of some important types of race conditions.
 858  */
 859 static int
 860 rcu_torture_fqs(void *arg)
 861 {
 862         unsigned long fqs_resume_time;
 863         int fqs_burst_remaining;
 864
 865         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 866         do {
 867                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 868                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 869                        !kthread_should_stop()) {
 870                         schedule_timeout_interruptible(1);
 871                 }
 872                 fqs_burst_remaining = fqs_duration;
 873                 while (fqs_burst_remaining > 0 &&
 874                        !kthread_should_stop()) {
 875                         cur_ops->fqs();
 876                         udelay(fqs_holdoff);
 877                         fqs_burst_remaining -= fqs_holdoff;
 878                 }
 879                 stutter_wait("rcu_torture_fqs");
 880         } while (!torture_must_stop());
 881         torture_kthread_stopping("rcu_torture_fqs");
 882         return 0;
 883 }
 884
 885 /*
 886  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 887  * for that pointed to by rcu_torture_current, freeing the old structure
 888  * after a series of grace periods (the "pipeline").
 889  */
 890 static int
 891 rcu_torture_writer(void *arg)
 892 {
 893         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 894         int expediting = 0;
 895         unsigned long gp_snap;
 896         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 897         bool gp_sync1 = gp_sync;
 898         int i;
 899         struct rcu_torture *rp;
 900         struct rcu_torture *old_rp;
 901         static DEFINE_TORTURE_RANDOM(rand);
 902         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 903                            RTWS_COND_GET, RTWS_SYNC };
 904         int nsynctypes = 0;
 905
 906         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 907         if (!can_expedite)
 908                 pr_alert("%s" TORTURE_FLAG
 909                          " GP expediting controlled from boot/sysfs for %s.\n",
 910                          torture_type, cur_ops->name);
 911
 912         /* Initialize synctype[] array.  If none set, take default. */
 913         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 914                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 915         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 916                 synctype[nsynctypes++] = RTWS_COND_GET;
 917                 pr_info("%s: Testing conditional GPs.\n", __func__);
 918         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 919                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 920         }
 921         if (gp_exp1 && cur_ops->exp_sync) {
 922                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 923                 pr_info("%s: Testing expedited GPs.\n", __func__);
 924         } else if (gp_exp && !cur_ops->exp_sync) {
 925                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 926         }
 927         if (gp_normal1 && cur_ops->deferred_free) {
 928                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 929                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 930         } else if (gp_normal && !cur_ops->deferred_free) {
 931                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 932         }
 933         if (gp_sync1 && cur_ops->sync) {
 934                 synctype[nsynctypes++] = RTWS_SYNC;
 935                 pr_info("%s: Testing normal GPs.\n", __func__);
 936         } else if (gp_sync && !cur_ops->sync) {
 937                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 938         }
 939         if (WARN_ONCE(nsynctypes == 0,
 940                       "rcu_torture_writer: No update-side primitives.\n")) {
 941                 /*
 942                  * No updates primitives, so don't try updating.
 943                  * The resulting test won't be testing much, hence the
 944                  * above WARN_ONCE().
 945                  */
 946                 rcu_torture_writer_state = RTWS_STOPPING;
 947                 torture_kthread_stopping("rcu_torture_writer");
 948         }
 949
 950         do {
 951                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 952                 schedule_timeout_uninterruptible(1);
 953                 rp = rcu_torture_alloc();
 954                 if (rp == NULL)
 955                         continue;
 956                 rp->rtort_pipe_count = 0;
 957                 rcu_torture_writer_state = RTWS_DELAY;
 958                 udelay(torture_random(&rand) & 0x3ff);
 959                 rcu_torture_writer_state = RTWS_REPLACE;
 960                 old_rp = rcu_dereference_check(rcu_torture_current,
 961                                                current == writer_task);
 962                 rp->rtort_mbtest = 1;
 963                 rcu_assign_pointer(rcu_torture_current, rp);
 964                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 965                 if (old_rp) {
 966                         i = old_rp->rtort_pipe_count;
 967                         if (i > RCU_TORTURE_PIPE_LEN)
 968                                 i = RCU_TORTURE_PIPE_LEN;
 969                         atomic_inc(&rcu_torture_wcount[i]);
 970                         old_rp->rtort_pipe_count++;
 971                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 972                         case RTWS_DEF_FREE:
 973                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 974                                 cur_ops->deferred_free(old_rp);
 975                                 break;
 976                         case RTWS_EXP_SYNC:
 977                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 978                                 cur_ops->exp_sync();
 979                                 rcu_torture_pipe_update(old_rp);
 980                                 break;
 981                         case RTWS_COND_GET:
 982                                 rcu_torture_writer_state = RTWS_COND_GET;
 983                                 gp_snap = cur_ops->get_state();
 984                                 i = torture_random(&rand) % 16;
 985                                 if (i != 0)
 986                                         schedule_timeout_interruptible(i);
 987                                 udelay(torture_random(&rand) % 1000);
 988                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 989                                 cur_ops->cond_sync(gp_snap);
 990                                 rcu_torture_pipe_update(old_rp);
 991                                 break;
 992                         case RTWS_SYNC:
 993                                 rcu_torture_writer_state = RTWS_SYNC;
 994                                 cur_ops->sync();
 995                                 rcu_torture_pipe_update(old_rp);
 996                                 break;
 997                         default:
 998                                 WARN_ON_ONCE(1);
 999                                 break;
1000                         }
1001                 }
1002                 WRITE_ONCE(rcu_torture_current_version,
1003                            rcu_torture_current_version + 1);
1004                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1005                 if (can_expedite &&
1006                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1007                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1008                         if (expediting >= 0)
1009                                 rcu_expedite_gp();
1010                         else
1011                                 rcu_unexpedite_gp();
1012                         if (++expediting > 3)
1013                                 expediting = -expediting;
1014                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1015                         can_expedite = !rcu_gp_is_expedited() &&
1016                                        !rcu_gp_is_normal();
1017                 }
1018                 rcu_torture_writer_state = RTWS_STUTTER;
1019                 if (stutter_wait("rcu_torture_writer"))
1020                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1021                                 if (list_empty(&rcu_tortures[i].rtort_free))
1022                                         WARN_ON_ONCE(1);
1023         } while (!torture_must_stop());
1024         /* Reset expediting back to unexpedited. */
1025         if (expediting > 0)
1026                 expediting = -expediting;
1027         while (can_expedite && expediting++ < 0)
1028                 rcu_unexpedite_gp();
1029         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1030         if (!can_expedite)
1031                 pr_alert("%s" TORTURE_FLAG
1032                          " Dynamic grace-period expediting was disabled.\n",
1033                          torture_type);
1034         rcu_torture_writer_state = RTWS_STOPPING;
1035         torture_kthread_stopping("rcu_torture_writer");
1036         return 0;
1037 }
1038
1039 /*
1040  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1041  * delay between calls.
1042  */
1043 static int
1044 rcu_torture_fakewriter(void *arg)
1045 {
1046         DEFINE_TORTURE_RANDOM(rand);
1047
1048         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1049         set_user_nice(current, MAX_NICE);
1050
1051         do {
1052                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1053                 udelay(torture_random(&rand) & 0x3ff);
1054                 if (cur_ops->cb_barrier != NULL &&
1055                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1056                         cur_ops->cb_barrier();
1057                 } else if (gp_normal == gp_exp) {
1058                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1059                                 cur_ops->sync();
1060                         else if (cur_ops->exp_sync)
1061                                 cur_ops->exp_sync();
1062                 } else if (gp_normal && cur_ops->sync) {
1063                         cur_ops->sync();
1064                 } else if (cur_ops->exp_sync) {
1065                         cur_ops->exp_sync();
1066                 }
1067                 stutter_wait("rcu_torture_fakewriter");
1068         } while (!torture_must_stop());
1069
1070         torture_kthread_stopping("rcu_torture_fakewriter");
1071         return 0;
1072 }
1073
1074 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1075 {
1076         kfree(rhp);
1077 }
1078
1079 /*
1080  * Do one extension of an RCU read-side critical section using the
1081  * current reader state in readstate (set to zero for initial entry
1082  * to extended critical section), set the new state as specified by
1083  * newstate (set to zero for final exit from extended critical section),
1084  * and random-number-generator state in trsp.  If this is neither the
1085  * beginning or end of the critical section and if there was actually a
1086  * change, do a ->read_delay().
1087  */
1088 static void rcutorture_one_extend(int *readstate, int newstate,
1089                                   struct torture_random_state *trsp,
1090                                   struct rt_read_seg *rtrsp)
1091 {
1092         int idxnew = -1;
1093         int idxold = *readstate;
1094         int statesnew = ~*readstate & newstate;
1095         int statesold = *readstate & ~newstate;
1096
1097         WARN_ON_ONCE(idxold < 0);
1098         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1099         rtrsp->rt_readstate = newstate;
1100
1101         /* First, put new protection in place to avoid critical-section gap. */
1102         if (statesnew & RCUTORTURE_RDR_BH)
1103                 local_bh_disable();
1104         if (statesnew & RCUTORTURE_RDR_IRQ)
1105                 local_irq_disable();
1106         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1107                 preempt_disable();
1108         if (statesnew & RCUTORTURE_RDR_RBH)
1109                 rcu_read_lock_bh();
1110         if (statesnew & RCUTORTURE_RDR_SCHED)
1111                 rcu_read_lock_sched();
1112         if (statesnew & RCUTORTURE_RDR_RCU)
1113                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1114
1115         /* Next, remove old protection, irq first due to bh conflict. */
1116         if (statesold & RCUTORTURE_RDR_IRQ)
1117                 local_irq_enable();
1118         if (statesold & RCUTORTURE_RDR_BH)
1119                 local_bh_enable();
1120         if (statesold & RCUTORTURE_RDR_PREEMPT)
1121                 preempt_enable();
1122         if (statesold & RCUTORTURE_RDR_RBH)
1123                 rcu_read_unlock_bh();
1124         if (statesold & RCUTORTURE_RDR_SCHED)
1125                 rcu_read_unlock_sched();
1126         if (statesold & RCUTORTURE_RDR_RCU)
1127                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1128
1129         /* Delay if neither beginning nor end and there was a change. */
1130         if ((statesnew || statesold) && *readstate && newstate)
1131                 cur_ops->read_delay(trsp, rtrsp);
1132
1133         /* Update the reader state. */
1134         if (idxnew == -1)
1135                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1136         WARN_ON_ONCE(idxnew < 0);
1137         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1138         *readstate = idxnew | newstate;
1139         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1140         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1141 }
1142
1143 /* Return the biggest extendables mask given current RCU and boot parameters. */
1144 static int rcutorture_extend_mask_max(void)
1145 {
1146         int mask;
1147
1148         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1149         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1150         mask = mask | RCUTORTURE_RDR_RCU;
1151         return mask;
1152 }
1153
1154 /* Return a random protection state mask, but with at least one bit set. */
1155 static int
1156 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1157 {
1158         int mask = rcutorture_extend_mask_max();
1159         unsigned long randmask1 = torture_random(trsp) >> 8;
1160         unsigned long randmask2 = randmask1 >> 3;
1161
1162         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1163         /* Most of the time lots of bits, half the time only one bit. */
1164         if (!(randmask1 & 0x7))
1165                 mask = mask & randmask2;
1166         else
1167                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1168         /* Can't enable bh w/irq disabled. */
1169         if ((mask & RCUTORTURE_RDR_IRQ) &&
1170             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1171              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1172                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1173         if ((mask & RCUTORTURE_RDR_IRQ) &&
1174             !(mask & cur_ops->ext_irq_conflict) &&
1175             (oldmask & cur_ops->ext_irq_conflict))
1176                 mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
1177         return mask ?: RCUTORTURE_RDR_RCU;
1178 }
1179
1180 /*
1181  * Do a randomly selected number of extensions of an existing RCU read-side
1182  * critical section.
1183  */
1184 static struct rt_read_seg *
1185 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1186                        struct rt_read_seg *rtrsp)
1187 {
1188         int i;
1189         int j;
1190         int mask = rcutorture_extend_mask_max();
1191
1192         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1193         if (!((mask - 1) & mask))
1194                 return rtrsp;  /* Current RCU reader not extendable. */
1195         /* Bias towards larger numbers of loops. */
1196         i = (torture_random(trsp) >> 3);
1197         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1198         for (j = 0; j < i; j++) {
1199                 mask = rcutorture_extend_mask(*readstate, trsp);
1200                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1201         }
1202         return &rtrsp[j];
1203 }
1204
1205 /*
1206  * Do one read-side critical section, returning false if there was
1207  * no data to read.  Can be invoked both from process context and
1208  * from a timer handler.
1209  */
1210 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1211 {
1212         int i;
1213         unsigned long started;
1214         unsigned long completed;
1215         int newstate;
1216         struct rcu_torture *p;
1217         int pipe_count;
1218         int readstate = 0;
1219         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1220         struct rt_read_seg *rtrsp = &rtseg[0];
1221         struct rt_read_seg *rtrsp1;
1222         unsigned long long ts;
1223
1224         newstate = rcutorture_extend_mask(readstate, trsp);
1225         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1226         started = cur_ops->get_gp_seq();
1227         ts = rcu_trace_clock_local();
1228         p = rcu_dereference_check(rcu_torture_current,
1229                                   rcu_read_lock_bh_held() ||
1230                                   rcu_read_lock_sched_held() ||
1231                                   srcu_read_lock_held(srcu_ctlp) ||
1232                                   torturing_tasks());
1233         if (p == NULL) {
1234                 /* Wait for rcu_torture_writer to get underway */
1235                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1236                 return false;
1237         }
1238         if (p->rtort_mbtest == 0)
1239                 atomic_inc(&n_rcu_torture_mberror);
1240         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1241         preempt_disable();
1242         pipe_count = p->rtort_pipe_count;
1243         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1244                 /* Should not happen, but... */
1245                 pipe_count = RCU_TORTURE_PIPE_LEN;
1246         }
1247         completed = cur_ops->get_gp_seq();
1248         if (pipe_count > 1) {
1249                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1250                                           ts, started, completed);
1251                 rcu_ftrace_dump(DUMP_ALL);
1252         }
1253         __this_cpu_inc(rcu_torture_count[pipe_count]);
1254         completed = rcutorture_seq_diff(completed, started);
1255         if (completed > RCU_TORTURE_PIPE_LEN) {
1256                 /* Should not happen, but... */
1257                 completed = RCU_TORTURE_PIPE_LEN;
1258         }
1259         __this_cpu_inc(rcu_torture_batch[completed]);
1260         preempt_enable();
1261         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1262         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1263
1264         /* If error or close call, record the sequence of reader protections. */
1265         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1266                 i = 0;
1267                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1268                         err_segs[i++] = *rtrsp1;
1269                 rt_read_nsegs = i;
1270         }
1271
1272         return true;
1273 }
1274
1275 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1276
1277 /*
1278  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1279  * incrementing the corresponding element of the pipeline array.  The
1280  * counter in the element should never be greater than 1, otherwise, the
1281  * RCU implementation is broken.
1282  */
1283 static void rcu_torture_timer(struct timer_list *unused)
1284 {
1285         atomic_long_inc(&n_rcu_torture_timers);
1286         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1287
1288         /* Test call_rcu() invocation from interrupt handler. */
1289         if (cur_ops->call) {
1290                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1291
1292                 if (rhp)
1293                         cur_ops->call(rhp, rcu_torture_timer_cb);
1294         }
1295 }
1296
1297 /*
1298  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1299  * incrementing the corresponding element of the pipeline array.  The
1300  * counter in the element should never be greater than 1, otherwise, the
1301  * RCU implementation is broken.
1302  */
1303 static int
1304 rcu_torture_reader(void *arg)
1305 {
1306         unsigned long lastsleep = jiffies;
1307         long myid = (long)arg;
1308         int mynumonline = myid;
1309         DEFINE_TORTURE_RANDOM(rand);
1310         struct timer_list t;
1311
1312         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1313         set_user_nice(current, MAX_NICE);
1314         if (irqreader && cur_ops->irq_capable)
1315                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1316
1317         do {
1318                 if (irqreader && cur_ops->irq_capable) {
1319                         if (!timer_pending(&t))
1320                                 mod_timer(&t, jiffies + 1);
1321                 }
1322                 if (!rcu_torture_one_read(&rand))
1323                         schedule_timeout_interruptible(HZ);
1324                 if (time_after(jiffies, lastsleep)) {
1325                         schedule_timeout_interruptible(1);
1326                         lastsleep = jiffies + 10;
1327                 }
1328                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1329                         schedule_timeout_interruptible(HZ / 5);
1330                 stutter_wait("rcu_torture_reader");
1331         } while (!torture_must_stop());
1332         if (irqreader && cur_ops->irq_capable) {
1333                 del_timer_sync(&t);
1334                 destroy_timer_on_stack(&t);
1335         }
1336         torture_kthread_stopping("rcu_torture_reader");
1337         return 0;
1338 }
1339
1340 /*
1341  * Print torture statistics.  Caller must ensure that there is only
1342  * one call to this function at a given time!!!  This is normally
1343  * accomplished by relying on the module system to only have one copy
1344  * of the module loaded, and then by giving the rcu_torture_stats
1345  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1346  * thread is not running).
1347  */
1348 static void
1349 rcu_torture_stats_print(void)
1350 {
1351         int cpu;
1352         int i;
1353         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1354         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1355         static unsigned long rtcv_snap = ULONG_MAX;
1356         static bool splatted;
1357         struct task_struct *wtp;
1358
1359         for_each_possible_cpu(cpu) {
1360                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1361                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1362                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1363                 }
1364         }
1365         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1366                 if (pipesummary[i] != 0)
1367                         break;
1368         }
1369
1370         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1371         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1372                 rcu_torture_current,
1373                 rcu_torture_current_version,
1374                 list_empty(&rcu_torture_freelist),
1375                 atomic_read(&n_rcu_torture_alloc),
1376                 atomic_read(&n_rcu_torture_alloc_fail),
1377                 atomic_read(&n_rcu_torture_free));
1378         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1379                 atomic_read(&n_rcu_torture_mberror),
1380                 n_rcu_torture_barrier_error,
1381                 n_rcu_torture_boost_ktrerror,
1382                 n_rcu_torture_boost_rterror);
1383         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1384                 n_rcu_torture_boost_failure,
1385                 n_rcu_torture_boosts,
1386                 atomic_long_read(&n_rcu_torture_timers));
1387         torture_onoff_stats();
1388         pr_cont("barrier: %ld/%ld:%ld\n",
1389                 n_barrier_successes,
1390                 n_barrier_attempts,
1391                 n_rcu_torture_barrier_error);
1392
1393         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1394         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1395             n_rcu_torture_barrier_error != 0 ||
1396             n_rcu_torture_boost_ktrerror != 0 ||
1397             n_rcu_torture_boost_rterror != 0 ||
1398             n_rcu_torture_boost_failure != 0 ||
1399             i > 1) {
1400                 pr_cont("%s", "!!! ");
1401                 atomic_inc(&n_rcu_torture_error);
1402                 WARN_ON_ONCE(1);
1403         }
1404         pr_cont("Reader Pipe: ");
1405         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1406                 pr_cont(" %ld", pipesummary[i]);
1407         pr_cont("\n");
1408
1409         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1410         pr_cont("Reader Batch: ");
1411         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1412                 pr_cont(" %ld", batchsummary[i]);
1413         pr_cont("\n");
1414
1415         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1416         pr_cont("Free-Block Circulation: ");
1417         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1418                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1419         }
1420         pr_cont("\n");
1421
1422         if (cur_ops->stats)
1423                 cur_ops->stats();
1424         if (rtcv_snap == rcu_torture_current_version &&
1425             rcu_torture_current != NULL) {
1426                 int __maybe_unused flags = 0;
1427                 unsigned long __maybe_unused gp_seq = 0;
1428
1429                 rcutorture_get_gp_data(cur_ops->ttype,
1430                                        &flags, &gp_seq);
1431                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1432                                         &flags, &gp_seq);
1433                 wtp = READ_ONCE(writer_task);
1434                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1435                          rcu_torture_writer_state_getname(),
1436                          rcu_torture_writer_state, gp_seq, flags,
1437                          wtp == NULL ? ~0UL : wtp->state,
1438                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1439                 if (!splatted && wtp) {
1440                         sched_show_task(wtp);
1441                         splatted = true;
1442                 }
1443                 show_rcu_gp_kthreads();
1444                 rcu_ftrace_dump(DUMP_ALL);
1445         }
1446         rtcv_snap = rcu_torture_current_version;
1447 }
1448
1449 /*
1450  * Periodically prints torture statistics, if periodic statistics printing
1451  * was specified via the stat_interval module parameter.
1452  */
1453 static int
1454 rcu_torture_stats(void *arg)
1455 {
1456         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1457         do {
1458                 schedule_timeout_interruptible(stat_interval * HZ);
1459                 rcu_torture_stats_print();
1460                 torture_shutdown_absorb("rcu_torture_stats");
1461         } while (!torture_must_stop());
1462         torture_kthread_stopping("rcu_torture_stats");
1463         return 0;
1464 }
1465
1466 static void
1467 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1468 {
1469         pr_alert("%s" TORTURE_FLAG
1470                  "--- %s: nreaders=%d nfakewriters=%d "
1471                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1472                  "shuffle_interval=%d stutter=%d irqreader=%d "
1473                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1474                  "test_boost=%d/%d test_boost_interval=%d "
1475                  "test_boost_duration=%d shutdown_secs=%d "
1476                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1477                  "n_barrier_cbs=%d "
1478                  "onoff_interval=%d onoff_holdoff=%d\n",
1479                  torture_type, tag, nrealreaders, nfakewriters,
1480                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1481                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1482                  test_boost, cur_ops->can_boost,
1483                  test_boost_interval, test_boost_duration, shutdown_secs,
1484                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1485                  n_barrier_cbs,
1486                  onoff_interval, onoff_holdoff);
1487 }
1488
1489 static int rcutorture_booster_cleanup(unsigned int cpu)
1490 {
1491         struct task_struct *t;
1492
1493         if (boost_tasks[cpu] == NULL)
1494                 return 0;
1495         mutex_lock(&boost_mutex);
1496         t = boost_tasks[cpu];
1497         boost_tasks[cpu] = NULL;
1498         rcu_torture_enable_rt_throttle();
1499         mutex_unlock(&boost_mutex);
1500
1501         /* This must be outside of the mutex, otherwise deadlock! */
1502         torture_stop_kthread(rcu_torture_boost, t);
1503         return 0;
1504 }
1505
1506 static int rcutorture_booster_init(unsigned int cpu)
1507 {
1508         int retval;
1509
1510         if (boost_tasks[cpu] != NULL)
1511                 return 0;  /* Already created, nothing more to do. */
1512
1513         /* Don't allow time recalculation while creating a new task. */
1514         mutex_lock(&boost_mutex);
1515         rcu_torture_disable_rt_throttle();
1516         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1517         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1518                                                   cpu_to_node(cpu),
1519                                                   "rcu_torture_boost");
1520         if (IS_ERR(boost_tasks[cpu])) {
1521                 retval = PTR_ERR(boost_tasks[cpu]);
1522                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1523                 n_rcu_torture_boost_ktrerror++;
1524                 boost_tasks[cpu] = NULL;
1525                 mutex_unlock(&boost_mutex);
1526                 return retval;
1527         }
1528         kthread_bind(boost_tasks[cpu], cpu);
1529         wake_up_process(boost_tasks[cpu]);
1530         mutex_unlock(&boost_mutex);
1531         return 0;
1532 }
1533
1534 /*
1535  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1536  * induces a CPU stall for the time specified by stall_cpu.
1537  */
1538 static int rcu_torture_stall(void *args)
1539 {
1540         unsigned long stop_at;
1541
1542         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1543         if (stall_cpu_holdoff > 0) {
1544                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1545                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1546                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1547         }
1548         if (!kthread_should_stop()) {
1549                 stop_at = ktime_get_seconds() + stall_cpu;
1550                 /* RCU CPU stall is expected behavior in following code. */
1551                 rcu_read_lock();
1552                 if (stall_cpu_irqsoff)
1553                         local_irq_disable();
1554                 else
1555                         preempt_disable();
1556                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1557                          smp_processor_id());
1558                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1559                                     stop_at))
1560                         continue;  /* Induce RCU CPU stall warning. */
1561                 if (stall_cpu_irqsoff)
1562                         local_irq_enable();
1563                 else
1564                         preempt_enable();
1565                 rcu_read_unlock();
1566                 pr_alert("rcu_torture_stall end.\n");
1567         }
1568         torture_shutdown_absorb("rcu_torture_stall");
1569         while (!kthread_should_stop())
1570                 schedule_timeout_interruptible(10 * HZ);
1571         return 0;
1572 }
1573
1574 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1575 static int __init rcu_torture_stall_init(void)
1576 {
1577         if (stall_cpu <= 0)
1578                 return 0;
1579         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1580 }
1581
1582 /* State structure for forward-progress self-propagating RCU callback. */
1583 struct fwd_cb_state {
1584         struct rcu_head rh;
1585         int stop;
1586 };
1587
1588 /*
1589  * Forward-progress self-propagating RCU callback function.  Because
1590  * callbacks run from softirq, this function is an implicit RCU read-side
1591  * critical section.
1592  */
1593 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1594 {
1595         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1596
1597         if (READ_ONCE(fcsp->stop)) {
1598                 WRITE_ONCE(fcsp->stop, 2);
1599                 return;
1600         }
1601         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1602 }
1603
1604 /* State for continuous-flood RCU callbacks. */
1605 struct rcu_fwd_cb {
1606         struct rcu_head rh;
1607         struct rcu_fwd_cb *rfc_next;
1608         int rfc_gps;
1609 };
1610 static DEFINE_SPINLOCK(rcu_fwd_lock);
1611 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1612 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1613 static long n_launders_cb;
1614 static unsigned long rcu_fwd_startat;
1615 static bool rcu_fwd_emergency_stop;
1616 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1617 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1618 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1619 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1620 struct rcu_launder_hist {
1621         long n_launders;
1622         unsigned long launder_gp_seq;
1623 };
1624 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1625 static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1626 static unsigned long rcu_launder_gp_seq_start;
1627
1628 static void rcu_torture_fwd_cb_hist(void)
1629 {
1630         unsigned long gps;
1631         unsigned long gps_old;
1632         int i;
1633         int j;
1634
1635         for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1636                 if (n_launders_hist[i].n_launders > 0)
1637                         break;
1638         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1639                  __func__, jiffies - rcu_fwd_startat);
1640         gps_old = rcu_launder_gp_seq_start;
1641         for (j = 0; j <= i; j++) {
1642                 gps = n_launders_hist[j].launder_gp_seq;
1643                 pr_cont(" %ds/%d: %ld:%ld",
1644                         j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1645                         rcutorture_seq_diff(gps, gps_old));
1646                 gps_old = gps;
1647         }
1648         pr_cont("\n");
1649 }
1650
1651 /* Callback function for continuous-flood RCU callbacks. */
1652 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1653 {
1654         unsigned long flags;
1655         int i;
1656         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1657         struct rcu_fwd_cb **rfcpp;
1658
1659         rfcp->rfc_next = NULL;
1660         rfcp->rfc_gps++;
1661         spin_lock_irqsave(&rcu_fwd_lock, flags);
1662         rfcpp = rcu_fwd_cb_tail;
1663         rcu_fwd_cb_tail = &rfcp->rfc_next;
1664         WRITE_ONCE(*rfcpp, rfcp);
1665         WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1666         i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1667         if (i >= ARRAY_SIZE(n_launders_hist))
1668                 i = ARRAY_SIZE(n_launders_hist) - 1;
1669         n_launders_hist[i].n_launders++;
1670         n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1671         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1672 }
1673
1674 /*
1675  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1676  * test is over or because we hit an OOM event.
1677  */
1678 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1679 {
1680         unsigned long flags;
1681         unsigned long freed = 0;
1682         struct rcu_fwd_cb *rfcp;
1683
1684         for (;;) {
1685                 spin_lock_irqsave(&rcu_fwd_lock, flags);
1686                 rfcp = rcu_fwd_cb_head;
1687                 if (!rfcp)
1688                         break;
1689                 rcu_fwd_cb_head = rfcp->rfc_next;
1690                 if (!rcu_fwd_cb_head)
1691                         rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1692                 spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1693                 kfree(rfcp);
1694                 freed++;
1695         }
1696         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1697         return freed;
1698 }
1699
1700 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1701 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1702 {
1703         unsigned long cver;
1704         unsigned long dur;
1705         struct fwd_cb_state fcs;
1706         unsigned long gps;
1707         int idx;
1708         int sd;
1709         int sd4;
1710         bool selfpropcb = false;
1711         unsigned long stopat;
1712         static DEFINE_TORTURE_RANDOM(trs);
1713
1714         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1715                 init_rcu_head_on_stack(&fcs.rh);
1716                 selfpropcb = true;
1717         }
1718
1719         /* Tight loop containing cond_resched(). */
1720         if  (selfpropcb) {
1721                 WRITE_ONCE(fcs.stop, 0);
1722                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1723         }
1724         cver = READ_ONCE(rcu_torture_current_version);
1725         gps = cur_ops->get_gp_seq();
1726         sd = cur_ops->stall_dur() + 1;
1727         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1728         dur = sd4 + torture_random(&trs) % (sd - sd4);
1729         WRITE_ONCE(rcu_fwd_startat, jiffies);
1730         stopat = rcu_fwd_startat + dur;
1731         while (time_before(jiffies, stopat) &&
1732                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1733                 idx = cur_ops->readlock();
1734                 udelay(10);
1735                 cur_ops->readunlock(idx);
1736                 if (!fwd_progress_need_resched || need_resched())
1737                         cond_resched();
1738         }
1739         (*tested_tries)++;
1740         if (!time_before(jiffies, stopat) &&
1741             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1742                 (*tested)++;
1743                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1744                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1745                 WARN_ON(!cver && gps < 2);
1746                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1747         }
1748         if (selfpropcb) {
1749                 WRITE_ONCE(fcs.stop, 1);
1750                 cur_ops->sync(); /* Wait for running CB to complete. */
1751                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1752         }
1753
1754         if (selfpropcb) {
1755                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1756                 destroy_rcu_head_on_stack(&fcs.rh);
1757         }
1758 }
1759
1760 /* Carry out call_rcu() forward-progress testing. */
1761 static void rcu_torture_fwd_prog_cr(void)
1762 {
1763         unsigned long cver;
1764         unsigned long gps;
1765         int i;
1766         long n_launders;
1767         long n_launders_cb_snap;
1768         long n_launders_sa;
1769         long n_max_cbs;
1770         long n_max_gps;
1771         struct rcu_fwd_cb *rfcp;
1772         struct rcu_fwd_cb *rfcpn;
1773         unsigned long stopat;
1774         unsigned long stoppedat;
1775
1776         if (READ_ONCE(rcu_fwd_emergency_stop))
1777                 return; /* Get out of the way quickly, no GP wait! */
1778
1779         /* Loop continuously posting RCU callbacks. */
1780         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1781         cur_ops->sync(); /* Later readers see above write. */
1782         WRITE_ONCE(rcu_fwd_startat, jiffies);
1783         stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1784         n_launders = 0;
1785         n_launders_cb = 0;
1786         n_launders_sa = 0;
1787         n_max_cbs = 0;
1788         n_max_gps = 0;
1789         for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1790                 n_launders_hist[i].n_launders = 0;
1791         cver = READ_ONCE(rcu_torture_current_version);
1792         gps = cur_ops->get_gp_seq();
1793         rcu_launder_gp_seq_start = gps;
1794         while (time_before(jiffies, stopat) &&
1795                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1796                 rfcp = READ_ONCE(rcu_fwd_cb_head);
1797                 rfcpn = NULL;
1798                 if (rfcp)
1799                         rfcpn = READ_ONCE(rfcp->rfc_next);
1800                 if (rfcpn) {
1801                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1802                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1803                                 break;
1804                         rcu_fwd_cb_head = rfcpn;
1805                         n_launders++;
1806                         n_launders_sa++;
1807                 } else {
1808                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1809                         if (WARN_ON_ONCE(!rfcp)) {
1810                                 schedule_timeout_interruptible(1);
1811                                 continue;
1812                         }
1813                         n_max_cbs++;
1814                         n_launders_sa = 0;
1815                         rfcp->rfc_gps = 0;
1816                 }
1817                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1818                 cond_resched();
1819         }
1820         stoppedat = jiffies;
1821         n_launders_cb_snap = READ_ONCE(n_launders_cb);
1822         cver = READ_ONCE(rcu_torture_current_version) - cver;
1823         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1824         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1825         (void)rcu_torture_fwd_prog_cbfree();
1826
1827         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1828         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
1829                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1830                 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",
1831                          __func__,
1832                          stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1833                          n_launders + n_max_cbs - n_launders_cb_snap,
1834                          n_launders, n_launders_sa,
1835                          n_max_gps, n_max_cbs, cver, gps);
1836                 rcu_torture_fwd_cb_hist();
1837         }
1838 }
1839
1840
1841 /*
1842  * OOM notifier, but this only prints diagnostic information for the
1843  * current forward-progress test.
1844  */
1845 static int rcutorture_oom_notify(struct notifier_block *self,
1846                                  unsigned long notused, void *nfreed)
1847 {
1848         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1849              __func__);
1850         rcu_torture_fwd_cb_hist();
1851         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2));
1852         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1853         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1854         pr_info("%s: Freed %lu RCU callbacks.\n",
1855                 __func__, rcu_torture_fwd_prog_cbfree());
1856         rcu_barrier();
1857         pr_info("%s: Freed %lu RCU callbacks.\n",
1858                 __func__, rcu_torture_fwd_prog_cbfree());
1859         rcu_barrier();
1860         pr_info("%s: Freed %lu RCU callbacks.\n",
1861                 __func__, rcu_torture_fwd_prog_cbfree());
1862         smp_mb(); /* Frees before return to avoid redoing OOM. */
1863         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1864         pr_info("%s returning after OOM processing.\n", __func__);
1865         return NOTIFY_OK;
1866 }
1867
1868 static struct notifier_block rcutorture_oom_nb = {
1869         .notifier_call = rcutorture_oom_notify
1870 };
1871
1872 /* Carry out grace-period forward-progress testing. */
1873 static int rcu_torture_fwd_prog(void *args)
1874 {
1875         int tested = 0;
1876         int tested_tries = 0;
1877
1878         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1879         rcu_bind_current_to_nocb();
1880         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1881                 set_user_nice(current, MAX_NICE);
1882         do {
1883                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1884                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
1885                 register_oom_notifier(&rcutorture_oom_nb);
1886                 rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1887                 rcu_torture_fwd_prog_cr();
1888                 unregister_oom_notifier(&rcutorture_oom_nb);
1889
1890                 /* Avoid slow periods, better to test when busy. */
1891                 stutter_wait("rcu_torture_fwd_prog");
1892         } while (!torture_must_stop());
1893         /* Short runs might not contain a valid forward-progress attempt. */
1894         WARN_ON(!tested && tested_tries >= 5);
1895         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1896         torture_kthread_stopping("rcu_torture_fwd_prog");
1897         return 0;
1898 }
1899
1900 /* If forward-progress checking is requested and feasible, spawn the thread. */
1901 static int __init rcu_torture_fwd_prog_init(void)
1902 {
1903         if (!fwd_progress)
1904                 return 0; /* Not requested, so don't do it. */
1905         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1906             cur_ops == &rcu_busted_ops) {
1907                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1908                 return 0;
1909         }
1910         if (stall_cpu > 0) {
1911                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1912                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1913                         return -EINVAL; /* In module, can fail back to user. */
1914                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1915                 return 0;
1916         }
1917         if (fwd_progress_holdoff <= 0)
1918                 fwd_progress_holdoff = 1;
1919         if (fwd_progress_div <= 0)
1920                 fwd_progress_div = 4;
1921         return torture_create_kthread(rcu_torture_fwd_prog,
1922                                       NULL, fwd_prog_task);
1923 }
1924
1925 /* Callback function for RCU barrier testing. */
1926 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1927 {
1928         atomic_inc(&barrier_cbs_invoked);
1929 }
1930
1931 /* kthread function to register callbacks used to test RCU barriers. */
1932 static int rcu_torture_barrier_cbs(void *arg)
1933 {
1934         long myid = (long)arg;
1935         bool lastphase = 0;
1936         bool newphase;
1937         struct rcu_head rcu;
1938
1939         init_rcu_head_on_stack(&rcu);
1940         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1941         set_user_nice(current, MAX_NICE);
1942         do {
1943                 wait_event(barrier_cbs_wq[myid],
1944                            (newphase =
1945                             smp_load_acquire(&barrier_phase)) != lastphase ||
1946                            torture_must_stop());
1947                 lastphase = newphase;
1948                 if (torture_must_stop())
1949                         break;
1950                 /*
1951                  * The above smp_load_acquire() ensures barrier_phase load
1952                  * is ordered before the following ->call().
1953                  */
1954                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1955                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1956                 local_irq_enable();
1957                 if (atomic_dec_and_test(&barrier_cbs_count))
1958                         wake_up(&barrier_wq);
1959         } while (!torture_must_stop());
1960         if (cur_ops->cb_barrier != NULL)
1961                 cur_ops->cb_barrier();
1962         destroy_rcu_head_on_stack(&rcu);
1963         torture_kthread_stopping("rcu_torture_barrier_cbs");
1964         return 0;
1965 }
1966
1967 /* kthread function to drive and coordinate RCU barrier testing. */
1968 static int rcu_torture_barrier(void *arg)
1969 {
1970         int i;
1971
1972         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1973         do {
1974                 atomic_set(&barrier_cbs_invoked, 0);
1975                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1976                 /* Ensure barrier_phase ordered after prior assignments. */
1977                 smp_store_release(&barrier_phase, !barrier_phase);
1978                 for (i = 0; i < n_barrier_cbs; i++)
1979                         wake_up(&barrier_cbs_wq[i]);
1980                 wait_event(barrier_wq,
1981                            atomic_read(&barrier_cbs_count) == 0 ||
1982                            torture_must_stop());
1983                 if (torture_must_stop())
1984                         break;
1985                 n_barrier_attempts++;
1986                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1987                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1988                         n_rcu_torture_barrier_error++;
1989                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1990                                atomic_read(&barrier_cbs_invoked),
1991                                n_barrier_cbs);
1992                         WARN_ON_ONCE(1);
1993                 } else {
1994                         n_barrier_successes++;
1995                 }
1996                 schedule_timeout_interruptible(HZ / 10);
1997         } while (!torture_must_stop());
1998         torture_kthread_stopping("rcu_torture_barrier");
1999         return 0;
2000 }
2001
2002 /* Initialize RCU barrier testing. */
2003 static int rcu_torture_barrier_init(void)
2004 {
2005         int i;
2006         int ret;
2007
2008         if (n_barrier_cbs <= 0)
2009                 return 0;
2010         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2011                 pr_alert("%s" TORTURE_FLAG
2012                          " Call or barrier ops missing for %s,\n",
2013                          torture_type, cur_ops->name);
2014                 pr_alert("%s" TORTURE_FLAG
2015                          " RCU barrier testing omitted from run.\n",
2016                          torture_type);
2017                 return 0;
2018         }
2019         atomic_set(&barrier_cbs_count, 0);
2020         atomic_set(&barrier_cbs_invoked, 0);
2021         barrier_cbs_tasks =
2022                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2023                         GFP_KERNEL);
2024         barrier_cbs_wq =
2025                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2026         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2027                 return -ENOMEM;
2028         for (i = 0; i < n_barrier_cbs; i++) {
2029                 init_waitqueue_head(&barrier_cbs_wq[i]);
2030                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2031                                              (void *)(long)i,
2032                                              barrier_cbs_tasks[i]);
2033                 if (ret)
2034                         return ret;
2035         }
2036         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2037 }
2038
2039 /* Clean up after RCU barrier testing. */
2040 static void rcu_torture_barrier_cleanup(void)
2041 {
2042         int i;
2043
2044         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2045         if (barrier_cbs_tasks != NULL) {
2046                 for (i = 0; i < n_barrier_cbs; i++)
2047                         torture_stop_kthread(rcu_torture_barrier_cbs,
2048                                              barrier_cbs_tasks[i]);
2049                 kfree(barrier_cbs_tasks);
2050                 barrier_cbs_tasks = NULL;
2051         }
2052         if (barrier_cbs_wq != NULL) {
2053                 kfree(barrier_cbs_wq);
2054                 barrier_cbs_wq = NULL;
2055         }
2056 }
2057
2058 static bool rcu_torture_can_boost(void)
2059 {
2060         static int boost_warn_once;
2061         int prio;
2062
2063         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2064                 return false;
2065
2066         prio = rcu_get_gp_kthreads_prio();
2067         if (!prio)
2068                 return false;
2069
2070         if (prio < 2) {
2071                 if (boost_warn_once  == 1)
2072                         return false;
2073
2074                 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);
2075                 boost_warn_once = 1;
2076                 return false;
2077         }
2078
2079         return true;
2080 }
2081
2082 static enum cpuhp_state rcutor_hp;
2083
2084 static void
2085 rcu_torture_cleanup(void)
2086 {
2087         int firsttime;
2088         int flags = 0;
2089         unsigned long gp_seq = 0;
2090         int i;
2091
2092         if (torture_cleanup_begin()) {
2093                 if (cur_ops->cb_barrier != NULL)
2094                         cur_ops->cb_barrier();
2095                 return;
2096         }
2097
2098         rcu_torture_barrier_cleanup();
2099         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2100         torture_stop_kthread(rcu_torture_stall, stall_task);
2101         torture_stop_kthread(rcu_torture_writer, writer_task);
2102
2103         if (reader_tasks) {
2104                 for (i = 0; i < nrealreaders; i++)
2105                         torture_stop_kthread(rcu_torture_reader,
2106                                              reader_tasks[i]);
2107                 kfree(reader_tasks);
2108         }
2109         rcu_torture_current = NULL;
2110
2111         if (fakewriter_tasks) {
2112                 for (i = 0; i < nfakewriters; i++) {
2113                         torture_stop_kthread(rcu_torture_fakewriter,
2114                                              fakewriter_tasks[i]);
2115                 }
2116                 kfree(fakewriter_tasks);
2117                 fakewriter_tasks = NULL;
2118         }
2119
2120         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2121         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2122         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2123                  cur_ops->name, gp_seq, flags);
2124         torture_stop_kthread(rcu_torture_stats, stats_task);
2125         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2126         if (rcu_torture_can_boost())
2127                 cpuhp_remove_state(rcutor_hp);
2128
2129         /*
2130          * Wait for all RCU callbacks to fire, then do torture-type-specific
2131          * cleanup operations.
2132          */
2133         if (cur_ops->cb_barrier != NULL)
2134                 cur_ops->cb_barrier();
2135         if (cur_ops->cleanup != NULL)
2136                 cur_ops->cleanup();
2137
2138         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2139
2140         if (err_segs_recorded) {
2141                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2142                 if (rt_read_nsegs == 0)
2143                         pr_alert("\t: No segments recorded!!!\n");
2144                 firsttime = 1;
2145                 for (i = 0; i < rt_read_nsegs; i++) {
2146                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2147                         if (err_segs[i].rt_delay_jiffies != 0) {
2148                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2149                                         err_segs[i].rt_delay_jiffies);
2150                                 firsttime = 0;
2151                         }
2152                         if (err_segs[i].rt_delay_ms != 0) {
2153                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2154                                         err_segs[i].rt_delay_ms);
2155                                 firsttime = 0;
2156                         }
2157                         if (err_segs[i].rt_delay_us != 0) {
2158                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2159                                         err_segs[i].rt_delay_us);
2160                                 firsttime = 0;
2161                         }
2162                         pr_cont("%s\n",
2163                                 err_segs[i].rt_preempted ? "preempted" : "");
2164
2165                 }
2166         }
2167         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2168                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2169         else if (torture_onoff_failures())
2170                 rcu_torture_print_module_parms(cur_ops,
2171                                                "End of test: RCU_HOTPLUG");
2172         else
2173                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2174         torture_cleanup_end();
2175 }
2176
2177 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2178 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2179 {
2180 }
2181
2182 static void rcu_torture_err_cb(struct rcu_head *rhp)
2183 {
2184         /*
2185          * This -might- happen due to race conditions, but is unlikely.
2186          * The scenario that leads to this happening is that the
2187          * first of the pair of duplicate callbacks is queued,
2188          * someone else starts a grace period that includes that
2189          * callback, then the second of the pair must wait for the
2190          * next grace period.  Unlikely, but can happen.  If it
2191          * does happen, the debug-objects subsystem won't have splatted.
2192          */
2193         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2194 }
2195 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2196
2197 /*
2198  * Verify that double-free causes debug-objects to complain, but only
2199  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2200  * cannot be carried out.
2201  */
2202 static void rcu_test_debug_objects(void)
2203 {
2204 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2205         struct rcu_head rh1;
2206         struct rcu_head rh2;
2207
2208         init_rcu_head_on_stack(&rh1);
2209         init_rcu_head_on_stack(&rh2);
2210         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2211
2212         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2213         preempt_disable(); /* Prevent preemption from interrupting test. */
2214         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2215         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2216         local_irq_disable(); /* Make it harder to start a new grace period. */
2217         call_rcu(&rh2, rcu_torture_leak_cb);
2218         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2219         local_irq_enable();
2220         rcu_read_unlock();
2221         preempt_enable();
2222
2223         /* Wait for them all to get done so we can safely return. */
2224         rcu_barrier();
2225         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2226         destroy_rcu_head_on_stack(&rh1);
2227         destroy_rcu_head_on_stack(&rh2);
2228 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2229         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2230 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2231 }
2232
2233 static void rcutorture_sync(void)
2234 {
2235         static unsigned long n;
2236
2237         if (cur_ops->sync && !(++n & 0xfff))
2238                 cur_ops->sync();
2239 }
2240
2241 static int __init
2242 rcu_torture_init(void)
2243 {
2244         long i;
2245         int cpu;
2246         int firsterr = 0;
2247         static struct rcu_torture_ops *torture_ops[] = {
2248                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2249                 &busted_srcud_ops, &tasks_ops,
2250         };
2251
2252         if (!torture_init_begin(torture_type, verbose))
2253                 return -EBUSY;
2254
2255         /* Process args and tell the world that the torturer is on the job. */
2256         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2257                 cur_ops = torture_ops[i];
2258                 if (strcmp(torture_type, cur_ops->name) == 0)
2259                         break;
2260         }
2261         if (i == ARRAY_SIZE(torture_ops)) {
2262                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2263                          torture_type);
2264                 pr_alert("rcu-torture types:");
2265                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2266                         pr_cont(" %s", torture_ops[i]->name);
2267                 pr_cont("\n");
2268                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2269                 firsterr = -EINVAL;
2270                 goto unwind;
2271         }
2272         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2273                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2274                 fqs_duration = 0;
2275         }
2276         if (cur_ops->init)
2277                 cur_ops->init();
2278
2279         if (nreaders >= 0) {
2280                 nrealreaders = nreaders;
2281         } else {
2282                 nrealreaders = num_online_cpus() - 2 - nreaders;
2283                 if (nrealreaders <= 0)
2284                         nrealreaders = 1;
2285         }
2286         rcu_torture_print_module_parms(cur_ops, "Start of test");
2287
2288         /* Set up the freelist. */
2289
2290         INIT_LIST_HEAD(&rcu_torture_freelist);
2291         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2292                 rcu_tortures[i].rtort_mbtest = 0;
2293                 list_add_tail(&rcu_tortures[i].rtort_free,
2294                               &rcu_torture_freelist);
2295         }
2296
2297         /* Initialize the statistics so that each run gets its own numbers. */
2298
2299         rcu_torture_current = NULL;
2300         rcu_torture_current_version = 0;
2301         atomic_set(&n_rcu_torture_alloc, 0);
2302         atomic_set(&n_rcu_torture_alloc_fail, 0);
2303         atomic_set(&n_rcu_torture_free, 0);
2304         atomic_set(&n_rcu_torture_mberror, 0);
2305         atomic_set(&n_rcu_torture_error, 0);
2306         n_rcu_torture_barrier_error = 0;
2307         n_rcu_torture_boost_ktrerror = 0;
2308         n_rcu_torture_boost_rterror = 0;
2309         n_rcu_torture_boost_failure = 0;
2310         n_rcu_torture_boosts = 0;
2311         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2312                 atomic_set(&rcu_torture_wcount[i], 0);
2313         for_each_possible_cpu(cpu) {
2314                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2315                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2316                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2317                 }
2318         }
2319         err_segs_recorded = 0;
2320         rt_read_nsegs = 0;
2321
2322         /* Start up the kthreads. */
2323
2324         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2325                                           writer_task);
2326         if (firsterr)
2327                 goto unwind;
2328         if (nfakewriters > 0) {
2329                 fakewriter_tasks = kcalloc(nfakewriters,
2330                                            sizeof(fakewriter_tasks[0]),
2331                                            GFP_KERNEL);
2332                 if (fakewriter_tasks == NULL) {
2333                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2334                         firsterr = -ENOMEM;
2335                         goto unwind;
2336                 }
2337         }
2338         for (i = 0; i < nfakewriters; i++) {
2339                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2340                                                   NULL, fakewriter_tasks[i]);
2341                 if (firsterr)
2342                         goto unwind;
2343         }
2344         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2345                                GFP_KERNEL);
2346         if (reader_tasks == NULL) {
2347                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2348                 firsterr = -ENOMEM;
2349                 goto unwind;
2350         }
2351         for (i = 0; i < nrealreaders; i++) {
2352                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2353                                                   reader_tasks[i]);
2354                 if (firsterr)
2355                         goto unwind;
2356         }
2357         if (stat_interval > 0) {
2358                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2359                                                   stats_task);
2360                 if (firsterr)
2361                         goto unwind;
2362         }
2363         if (test_no_idle_hz && shuffle_interval > 0) {
2364                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2365                 if (firsterr)
2366                         goto unwind;
2367         }
2368         if (stutter < 0)
2369                 stutter = 0;
2370         if (stutter) {
2371                 firsterr = torture_stutter_init(stutter * HZ);
2372                 if (firsterr)
2373                         goto unwind;
2374         }
2375         if (fqs_duration < 0)
2376                 fqs_duration = 0;
2377         if (fqs_duration) {
2378                 /* Create the fqs thread */
2379                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2380                                                   fqs_task);
2381                 if (firsterr)
2382                         goto unwind;
2383         }
2384         if (test_boost_interval < 1)
2385                 test_boost_interval = 1;
2386         if (test_boost_duration < 2)
2387                 test_boost_duration = 2;
2388         if (rcu_torture_can_boost()) {
2389
2390                 boost_starttime = jiffies + test_boost_interval * HZ;
2391
2392                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2393                                              rcutorture_booster_init,
2394                                              rcutorture_booster_cleanup);
2395                 if (firsterr < 0)
2396                         goto unwind;
2397                 rcutor_hp = firsterr;
2398         }
2399         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2400         if (firsterr)
2401                 goto unwind;
2402         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2403                                       rcutorture_sync);
2404         if (firsterr)
2405                 goto unwind;
2406         firsterr = rcu_torture_stall_init();
2407         if (firsterr)
2408                 goto unwind;
2409         firsterr = rcu_torture_fwd_prog_init();
2410         if (firsterr)
2411                 goto unwind;
2412         firsterr = rcu_torture_barrier_init();
2413         if (firsterr)
2414                 goto unwind;
2415         if (object_debug)
2416                 rcu_test_debug_objects();
2417         torture_init_end();
2418         return 0;
2419
2420 unwind:
2421         torture_init_end();
2422         rcu_torture_cleanup();
2423         return firsterr;
2424 }
2425
2426 module_init(rcu_torture_init);
2427 module_exit(rcu_torture_cleanup);