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 slow_gps;
 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         cleanup_srcu_struct(&srcu_ctld);
 596         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 597 }
 598
 599 /* As above, but dynamically allocated. */
 600 static struct rcu_torture_ops srcud_ops = {
 601         .ttype          = SRCU_FLAVOR,
 602         .init           = srcu_torture_init,
 603         .cleanup        = srcu_torture_cleanup,
 604         .readlock       = srcu_torture_read_lock,
 605         .read_delay     = srcu_read_delay,
 606         .readunlock     = srcu_torture_read_unlock,
 607         .get_gp_seq     = srcu_torture_completed,
 608         .deferred_free  = srcu_torture_deferred_free,
 609         .sync           = srcu_torture_synchronize,
 610         .exp_sync       = srcu_torture_synchronize_expedited,
 611         .call           = srcu_torture_call,
 612         .cb_barrier     = srcu_torture_barrier,
 613         .stats          = srcu_torture_stats,
 614         .irq_capable    = 1,
 615         .name           = "srcud"
 616 };
 617
 618 /* As above, but broken due to inappropriate reader extension. */
 619 static struct rcu_torture_ops busted_srcud_ops = {
 620         .ttype          = SRCU_FLAVOR,
 621         .init           = srcu_torture_init,
 622         .cleanup        = srcu_torture_cleanup,
 623         .readlock       = srcu_torture_read_lock,
 624         .read_delay     = rcu_read_delay,
 625         .readunlock     = srcu_torture_read_unlock,
 626         .get_gp_seq     = srcu_torture_completed,
 627         .deferred_free  = srcu_torture_deferred_free,
 628         .sync           = srcu_torture_synchronize,
 629         .exp_sync       = srcu_torture_synchronize_expedited,
 630         .call           = srcu_torture_call,
 631         .cb_barrier     = srcu_torture_barrier,
 632         .stats          = srcu_torture_stats,
 633         .irq_capable    = 1,
 634         .extendables    = RCUTORTURE_MAX_EXTEND,
 635         .name           = "busted_srcud"
 636 };
 637
 638 /*
 639  * Definitions for RCU-tasks torture testing.
 640  */
 641
 642 static int tasks_torture_read_lock(void)
 643 {
 644         return 0;
 645 }
 646
 647 static void tasks_torture_read_unlock(int idx)
 648 {
 649 }
 650
 651 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 652 {
 653         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 654 }
 655
 656 static struct rcu_torture_ops tasks_ops = {
 657         .ttype          = RCU_TASKS_FLAVOR,
 658         .init           = rcu_sync_torture_init,
 659         .readlock       = tasks_torture_read_lock,
 660         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 661         .readunlock     = tasks_torture_read_unlock,
 662         .get_gp_seq     = rcu_no_completed,
 663         .deferred_free  = rcu_tasks_torture_deferred_free,
 664         .sync           = synchronize_rcu_tasks,
 665         .exp_sync       = synchronize_rcu_tasks,
 666         .call           = call_rcu_tasks,
 667         .cb_barrier     = rcu_barrier_tasks,
 668         .fqs            = NULL,
 669         .stats          = NULL,
 670         .irq_capable    = 1,
 671         .slow_gps       = 1,
 672         .name           = "tasks"
 673 };
 674
 675 /*
 676  * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 677  * This implementation does not necessarily work well with CPU hotplug.
 678  */
 679
 680 static void synchronize_rcu_trivial(void)
 681 {
 682         int cpu;
 683
 684         for_each_online_cpu(cpu) {
 685                 rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 686                 WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 687         }
 688 }
 689
 690 static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 691 {
 692         preempt_disable();
 693         return 0;
 694 }
 695
 696 static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 697 {
 698         preempt_enable();
 699 }
 700
 701 static struct rcu_torture_ops trivial_ops = {
 702         .ttype          = RCU_TRIVIAL_FLAVOR,
 703         .init           = rcu_sync_torture_init,
 704         .readlock       = rcu_torture_read_lock_trivial,
 705         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 706         .readunlock     = rcu_torture_read_unlock_trivial,
 707         .get_gp_seq     = rcu_no_completed,
 708         .sync           = synchronize_rcu_trivial,
 709         .exp_sync       = synchronize_rcu_trivial,
 710         .fqs            = NULL,
 711         .stats          = NULL,
 712         .irq_capable    = 1,
 713         .name           = "trivial"
 714 };
 715
 716 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 717 {
 718         if (!cur_ops->gp_diff)
 719                 return new - old;
 720         return cur_ops->gp_diff(new, old);
 721 }
 722
 723 static bool __maybe_unused torturing_tasks(void)
 724 {
 725         return cur_ops == &tasks_ops;
 726 }
 727
 728 /*
 729  * RCU torture priority-boost testing.  Runs one real-time thread per
 730  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 731  * spinning waiting for them to be invoked.  If a given callback takes
 732  * too long to be invoked, we assume that priority inversion has occurred.
 733  */
 734
 735 struct rcu_boost_inflight {
 736         struct rcu_head rcu;
 737         int inflight;
 738 };
 739
 740 static void rcu_torture_boost_cb(struct rcu_head *head)
 741 {
 742         struct rcu_boost_inflight *rbip =
 743                 container_of(head, struct rcu_boost_inflight, rcu);
 744
 745         /* Ensure RCU-core accesses precede clearing ->inflight */
 746         smp_store_release(&rbip->inflight, 0);
 747 }
 748
 749 static int old_rt_runtime = -1;
 750
 751 static void rcu_torture_disable_rt_throttle(void)
 752 {
 753         /*
 754          * Disable RT throttling so that rcutorture's boost threads don't get
 755          * throttled. Only possible if rcutorture is built-in otherwise the
 756          * user should manually do this by setting the sched_rt_period_us and
 757          * sched_rt_runtime sysctls.
 758          */
 759         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 760                 return;
 761
 762         old_rt_runtime = sysctl_sched_rt_runtime;
 763         sysctl_sched_rt_runtime = -1;
 764 }
 765
 766 static void rcu_torture_enable_rt_throttle(void)
 767 {
 768         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 769                 return;
 770
 771         sysctl_sched_rt_runtime = old_rt_runtime;
 772         old_rt_runtime = -1;
 773 }
 774
 775 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 776 {
 777         if (end - start > test_boost_duration * HZ - HZ / 2) {
 778                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 779                 n_rcu_torture_boost_failure++;
 780
 781                 return true; /* failed */
 782         }
 783
 784         return false; /* passed */
 785 }
 786
 787 static int rcu_torture_boost(void *arg)
 788 {
 789         unsigned long call_rcu_time;
 790         unsigned long endtime;
 791         unsigned long oldstarttime;
 792         struct rcu_boost_inflight rbi = { .inflight = 0 };
 793         struct sched_param sp;
 794
 795         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 796
 797         /* Set real-time priority. */
 798         sp.sched_priority = 1;
 799         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 800                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 801                 n_rcu_torture_boost_rterror++;
 802         }
 803
 804         init_rcu_head_on_stack(&rbi.rcu);
 805         /* Each pass through the following loop does one boost-test cycle. */
 806         do {
 807                 /* Track if the test failed already in this test interval? */
 808                 bool failed = false;
 809
 810                 /* Increment n_rcu_torture_boosts once per boost-test */
 811                 while (!kthread_should_stop()) {
 812                         if (mutex_trylock(&boost_mutex)) {
 813                                 n_rcu_torture_boosts++;
 814                                 mutex_unlock(&boost_mutex);
 815                                 break;
 816                         }
 817                         schedule_timeout_uninterruptible(1);
 818                 }
 819                 if (kthread_should_stop())
 820                         goto checkwait;
 821
 822                 /* Wait for the next test interval. */
 823                 oldstarttime = boost_starttime;
 824                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 825                         schedule_timeout_interruptible(oldstarttime - jiffies);
 826                         stutter_wait("rcu_torture_boost");
 827                         if (torture_must_stop())
 828                                 goto checkwait;
 829                 }
 830
 831                 /* Do one boost-test interval. */
 832                 endtime = oldstarttime + test_boost_duration * HZ;
 833                 call_rcu_time = jiffies;
 834                 while (ULONG_CMP_LT(jiffies, endtime)) {
 835                         /* If we don't have a callback in flight, post one. */
 836                         if (!smp_load_acquire(&rbi.inflight)) {
 837                                 /* RCU core before ->inflight = 1. */
 838                                 smp_store_release(&rbi.inflight, 1);
 839                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 840                                 /* Check if the boost test failed */
 841                                 failed = failed ||
 842                                          rcu_torture_boost_failed(call_rcu_time,
 843                                                                  jiffies);
 844                                 call_rcu_time = jiffies;
 845                         }
 846                         stutter_wait("rcu_torture_boost");
 847                         if (torture_must_stop())
 848                                 goto checkwait;
 849                 }
 850
 851                 /*
 852                  * If boost never happened, then inflight will always be 1, in
 853                  * this case the boost check would never happen in the above
 854                  * loop so do another one here.
 855                  */
 856                 if (!failed && smp_load_acquire(&rbi.inflight))
 857                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 858
 859                 /*
 860                  * Set the start time of the next test interval.
 861                  * Yes, this is vulnerable to long delays, but such
 862                  * delays simply cause a false negative for the next
 863                  * interval.  Besides, we are running at RT priority,
 864                  * so delays should be relatively rare.
 865                  */
 866                 while (oldstarttime == boost_starttime &&
 867                        !kthread_should_stop()) {
 868                         if (mutex_trylock(&boost_mutex)) {
 869                                 boost_starttime = jiffies +
 870                                                   test_boost_interval * HZ;
 871                                 mutex_unlock(&boost_mutex);
 872                                 break;
 873                         }
 874                         schedule_timeout_uninterruptible(1);
 875                 }
 876
 877                 /* Go do the stutter. */
 878 checkwait:      stutter_wait("rcu_torture_boost");
 879         } while (!torture_must_stop());
 880
 881         /* Clean up and exit. */
 882         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 883                 torture_shutdown_absorb("rcu_torture_boost");
 884                 schedule_timeout_uninterruptible(1);
 885         }
 886         destroy_rcu_head_on_stack(&rbi.rcu);
 887         torture_kthread_stopping("rcu_torture_boost");
 888         return 0;
 889 }
 890
 891 /*
 892  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 893  * bursts of calls to force_quiescent_state(), increasing the probability
 894  * of occurrence of some important types of race conditions.
 895  */
 896 static int
 897 rcu_torture_fqs(void *arg)
 898 {
 899         unsigned long fqs_resume_time;
 900         int fqs_burst_remaining;
 901
 902         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 903         do {
 904                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 905                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 906                        !kthread_should_stop()) {
 907                         schedule_timeout_interruptible(1);
 908                 }
 909                 fqs_burst_remaining = fqs_duration;
 910                 while (fqs_burst_remaining > 0 &&
 911                        !kthread_should_stop()) {
 912                         cur_ops->fqs();
 913                         udelay(fqs_holdoff);
 914                         fqs_burst_remaining -= fqs_holdoff;
 915                 }
 916                 stutter_wait("rcu_torture_fqs");
 917         } while (!torture_must_stop());
 918         torture_kthread_stopping("rcu_torture_fqs");
 919         return 0;
 920 }
 921
 922 /*
 923  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 924  * for that pointed to by rcu_torture_current, freeing the old structure
 925  * after a series of grace periods (the "pipeline").
 926  */
 927 static int
 928 rcu_torture_writer(void *arg)
 929 {
 930         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 931         int expediting = 0;
 932         unsigned long gp_snap;
 933         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 934         bool gp_sync1 = gp_sync;
 935         int i;
 936         struct rcu_torture *rp;
 937         struct rcu_torture *old_rp;
 938         static DEFINE_TORTURE_RANDOM(rand);
 939         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 940                            RTWS_COND_GET, RTWS_SYNC };
 941         int nsynctypes = 0;
 942
 943         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 944         if (!can_expedite)
 945                 pr_alert("%s" TORTURE_FLAG
 946                          " GP expediting controlled from boot/sysfs for %s.\n",
 947                          torture_type, cur_ops->name);
 948
 949         /* Initialize synctype[] array.  If none set, take default. */
 950         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 951                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 952         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 953                 synctype[nsynctypes++] = RTWS_COND_GET;
 954                 pr_info("%s: Testing conditional GPs.\n", __func__);
 955         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 956                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 957         }
 958         if (gp_exp1 && cur_ops->exp_sync) {
 959                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 960                 pr_info("%s: Testing expedited GPs.\n", __func__);
 961         } else if (gp_exp && !cur_ops->exp_sync) {
 962                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 963         }
 964         if (gp_normal1 && cur_ops->deferred_free) {
 965                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 966                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 967         } else if (gp_normal && !cur_ops->deferred_free) {
 968                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 969         }
 970         if (gp_sync1 && cur_ops->sync) {
 971                 synctype[nsynctypes++] = RTWS_SYNC;
 972                 pr_info("%s: Testing normal GPs.\n", __func__);
 973         } else if (gp_sync && !cur_ops->sync) {
 974                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 975         }
 976         if (WARN_ONCE(nsynctypes == 0,
 977                       "rcu_torture_writer: No update-side primitives.\n")) {
 978                 /*
 979                  * No updates primitives, so don't try updating.
 980                  * The resulting test won't be testing much, hence the
 981                  * above WARN_ONCE().
 982                  */
 983                 rcu_torture_writer_state = RTWS_STOPPING;
 984                 torture_kthread_stopping("rcu_torture_writer");
 985         }
 986
 987         do {
 988                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 989                 schedule_timeout_uninterruptible(1);
 990                 rp = rcu_torture_alloc();
 991                 if (rp == NULL)
 992                         continue;
 993                 rp->rtort_pipe_count = 0;
 994                 rcu_torture_writer_state = RTWS_DELAY;
 995                 udelay(torture_random(&rand) & 0x3ff);
 996                 rcu_torture_writer_state = RTWS_REPLACE;
 997                 old_rp = rcu_dereference_check(rcu_torture_current,
 998                                                current == writer_task);
 999                 rp->rtort_mbtest = 1;
1000                 rcu_assign_pointer(rcu_torture_current, rp);
1001                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1002                 if (old_rp) {
1003                         i = old_rp->rtort_pipe_count;
1004                         if (i > RCU_TORTURE_PIPE_LEN)
1005                                 i = RCU_TORTURE_PIPE_LEN;
1006                         atomic_inc(&rcu_torture_wcount[i]);
1007                         old_rp->rtort_pipe_count++;
1008                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1009                         case RTWS_DEF_FREE:
1010                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1011                                 cur_ops->deferred_free(old_rp);
1012                                 break;
1013                         case RTWS_EXP_SYNC:
1014                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1015                                 cur_ops->exp_sync();
1016                                 rcu_torture_pipe_update(old_rp);
1017                                 break;
1018                         case RTWS_COND_GET:
1019                                 rcu_torture_writer_state = RTWS_COND_GET;
1020                                 gp_snap = cur_ops->get_state();
1021                                 i = torture_random(&rand) % 16;
1022                                 if (i != 0)
1023                                         schedule_timeout_interruptible(i);
1024                                 udelay(torture_random(&rand) % 1000);
1025                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1026                                 cur_ops->cond_sync(gp_snap);
1027                                 rcu_torture_pipe_update(old_rp);
1028                                 break;
1029                         case RTWS_SYNC:
1030                                 rcu_torture_writer_state = RTWS_SYNC;
1031                                 cur_ops->sync();
1032                                 rcu_torture_pipe_update(old_rp);
1033                                 break;
1034                         default:
1035                                 WARN_ON_ONCE(1);
1036                                 break;
1037                         }
1038                 }
1039                 WRITE_ONCE(rcu_torture_current_version,
1040                            rcu_torture_current_version + 1);
1041                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1042                 if (can_expedite &&
1043                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1044                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1045                         if (expediting >= 0)
1046                                 rcu_expedite_gp();
1047                         else
1048                                 rcu_unexpedite_gp();
1049                         if (++expediting > 3)
1050                                 expediting = -expediting;
1051                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1052                         can_expedite = !rcu_gp_is_expedited() &&
1053                                        !rcu_gp_is_normal();
1054                 }
1055                 rcu_torture_writer_state = RTWS_STUTTER;
1056                 if (stutter_wait("rcu_torture_writer") &&
1057                     !READ_ONCE(rcu_fwd_cb_nodelay) &&
1058                     !cur_ops->slow_gps &&
1059                     !torture_must_stop())
1060                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1061                                 if (list_empty(&rcu_tortures[i].rtort_free) &&
1062                                     rcu_access_pointer(rcu_torture_current) !=
1063                                     &rcu_tortures[i]) {
1064                                         rcu_ftrace_dump(DUMP_ALL);
1065                                         WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1066                                 }
1067         } while (!torture_must_stop());
1068         /* Reset expediting back to unexpedited. */
1069         if (expediting > 0)
1070                 expediting = -expediting;
1071         while (can_expedite && expediting++ < 0)
1072                 rcu_unexpedite_gp();
1073         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1074         if (!can_expedite)
1075                 pr_alert("%s" TORTURE_FLAG
1076                          " Dynamic grace-period expediting was disabled.\n",
1077                          torture_type);
1078         rcu_torture_writer_state = RTWS_STOPPING;
1079         torture_kthread_stopping("rcu_torture_writer");
1080         return 0;
1081 }
1082
1083 /*
1084  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1085  * delay between calls.
1086  */
1087 static int
1088 rcu_torture_fakewriter(void *arg)
1089 {
1090         DEFINE_TORTURE_RANDOM(rand);
1091
1092         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1093         set_user_nice(current, MAX_NICE);
1094
1095         do {
1096                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1097                 udelay(torture_random(&rand) & 0x3ff);
1098                 if (cur_ops->cb_barrier != NULL &&
1099                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1100                         cur_ops->cb_barrier();
1101                 } else if (gp_normal == gp_exp) {
1102                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1103                                 cur_ops->sync();
1104                         else if (cur_ops->exp_sync)
1105                                 cur_ops->exp_sync();
1106                 } else if (gp_normal && cur_ops->sync) {
1107                         cur_ops->sync();
1108                 } else if (cur_ops->exp_sync) {
1109                         cur_ops->exp_sync();
1110                 }
1111                 stutter_wait("rcu_torture_fakewriter");
1112         } while (!torture_must_stop());
1113
1114         torture_kthread_stopping("rcu_torture_fakewriter");
1115         return 0;
1116 }
1117
1118 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1119 {
1120         kfree(rhp);
1121 }
1122
1123 /*
1124  * Do one extension of an RCU read-side critical section using the
1125  * current reader state in readstate (set to zero for initial entry
1126  * to extended critical section), set the new state as specified by
1127  * newstate (set to zero for final exit from extended critical section),
1128  * and random-number-generator state in trsp.  If this is neither the
1129  * beginning or end of the critical section and if there was actually a
1130  * change, do a ->read_delay().
1131  */
1132 static void rcutorture_one_extend(int *readstate, int newstate,
1133                                   struct torture_random_state *trsp,
1134                                   struct rt_read_seg *rtrsp)
1135 {
1136         int idxnew = -1;
1137         int idxold = *readstate;
1138         int statesnew = ~*readstate & newstate;
1139         int statesold = *readstate & ~newstate;
1140
1141         WARN_ON_ONCE(idxold < 0);
1142         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1143         rtrsp->rt_readstate = newstate;
1144
1145         /* First, put new protection in place to avoid critical-section gap. */
1146         if (statesnew & RCUTORTURE_RDR_BH)
1147                 local_bh_disable();
1148         if (statesnew & RCUTORTURE_RDR_IRQ)
1149                 local_irq_disable();
1150         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1151                 preempt_disable();
1152         if (statesnew & RCUTORTURE_RDR_RBH)
1153                 rcu_read_lock_bh();
1154         if (statesnew & RCUTORTURE_RDR_SCHED)
1155                 rcu_read_lock_sched();
1156         if (statesnew & RCUTORTURE_RDR_RCU)
1157                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1158
1159         /* Next, remove old protection, irq first due to bh conflict. */
1160         if (statesold & RCUTORTURE_RDR_IRQ)
1161                 local_irq_enable();
1162         if (statesold & RCUTORTURE_RDR_BH)
1163                 local_bh_enable();
1164         if (statesold & RCUTORTURE_RDR_PREEMPT)
1165                 preempt_enable();
1166         if (statesold & RCUTORTURE_RDR_RBH)
1167                 rcu_read_unlock_bh();
1168         if (statesold & RCUTORTURE_RDR_SCHED)
1169                 rcu_read_unlock_sched();
1170         if (statesold & RCUTORTURE_RDR_RCU)
1171                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1172
1173         /* Delay if neither beginning nor end and there was a change. */
1174         if ((statesnew || statesold) && *readstate && newstate)
1175                 cur_ops->read_delay(trsp, rtrsp);
1176
1177         /* Update the reader state. */
1178         if (idxnew == -1)
1179                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1180         WARN_ON_ONCE(idxnew < 0);
1181         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1182         *readstate = idxnew | newstate;
1183         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1184         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1185 }
1186
1187 /* Return the biggest extendables mask given current RCU and boot parameters. */
1188 static int rcutorture_extend_mask_max(void)
1189 {
1190         int mask;
1191
1192         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1193         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1194         mask = mask | RCUTORTURE_RDR_RCU;
1195         return mask;
1196 }
1197
1198 /* Return a random protection state mask, but with at least one bit set. */
1199 static int
1200 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1201 {
1202         int mask = rcutorture_extend_mask_max();
1203         unsigned long randmask1 = torture_random(trsp) >> 8;
1204         unsigned long randmask2 = randmask1 >> 3;
1205
1206         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1207         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1208         if (!(randmask1 & 0x7))
1209                 mask = mask & randmask2;
1210         else
1211                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1212         /* Can't enable bh w/irq disabled. */
1213         if ((mask & RCUTORTURE_RDR_IRQ) &&
1214             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1215              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1216                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1217         return mask ?: RCUTORTURE_RDR_RCU;
1218 }
1219
1220 /*
1221  * Do a randomly selected number of extensions of an existing RCU read-side
1222  * critical section.
1223  */
1224 static struct rt_read_seg *
1225 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1226                        struct rt_read_seg *rtrsp)
1227 {
1228         int i;
1229         int j;
1230         int mask = rcutorture_extend_mask_max();
1231
1232         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1233         if (!((mask - 1) & mask))
1234                 return rtrsp;  /* Current RCU reader not extendable. */
1235         /* Bias towards larger numbers of loops. */
1236         i = (torture_random(trsp) >> 3);
1237         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1238         for (j = 0; j < i; j++) {
1239                 mask = rcutorture_extend_mask(*readstate, trsp);
1240                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1241         }
1242         return &rtrsp[j];
1243 }
1244
1245 /*
1246  * Do one read-side critical section, returning false if there was
1247  * no data to read.  Can be invoked both from process context and
1248  * from a timer handler.
1249  */
1250 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1251 {
1252         int i;
1253         unsigned long started;
1254         unsigned long completed;
1255         int newstate;
1256         struct rcu_torture *p;
1257         int pipe_count;
1258         int readstate = 0;
1259         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1260         struct rt_read_seg *rtrsp = &rtseg[0];
1261         struct rt_read_seg *rtrsp1;
1262         unsigned long long ts;
1263
1264         newstate = rcutorture_extend_mask(readstate, trsp);
1265         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1266         started = cur_ops->get_gp_seq();
1267         ts = rcu_trace_clock_local();
1268         p = rcu_dereference_check(rcu_torture_current,
1269                                   rcu_read_lock_bh_held() ||
1270                                   rcu_read_lock_sched_held() ||
1271                                   srcu_read_lock_held(srcu_ctlp) ||
1272                                   torturing_tasks());
1273         if (p == NULL) {
1274                 /* Wait for rcu_torture_writer to get underway */
1275                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1276                 return false;
1277         }
1278         if (p->rtort_mbtest == 0)
1279                 atomic_inc(&n_rcu_torture_mberror);
1280         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1281         preempt_disable();
1282         pipe_count = p->rtort_pipe_count;
1283         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1284                 /* Should not happen, but... */
1285                 pipe_count = RCU_TORTURE_PIPE_LEN;
1286         }
1287         completed = cur_ops->get_gp_seq();
1288         if (pipe_count > 1) {
1289                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1290                                           ts, started, completed);
1291                 rcu_ftrace_dump(DUMP_ALL);
1292         }
1293         __this_cpu_inc(rcu_torture_count[pipe_count]);
1294         completed = rcutorture_seq_diff(completed, started);
1295         if (completed > RCU_TORTURE_PIPE_LEN) {
1296                 /* Should not happen, but... */
1297                 completed = RCU_TORTURE_PIPE_LEN;
1298         }
1299         __this_cpu_inc(rcu_torture_batch[completed]);
1300         preempt_enable();
1301         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1302         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1303
1304         /* If error or close call, record the sequence of reader protections. */
1305         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1306                 i = 0;
1307                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1308                         err_segs[i++] = *rtrsp1;
1309                 rt_read_nsegs = i;
1310         }
1311
1312         return true;
1313 }
1314
1315 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1316
1317 /*
1318  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1319  * incrementing the corresponding element of the pipeline array.  The
1320  * counter in the element should never be greater than 1, otherwise, the
1321  * RCU implementation is broken.
1322  */
1323 static void rcu_torture_timer(struct timer_list *unused)
1324 {
1325         atomic_long_inc(&n_rcu_torture_timers);
1326         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1327
1328         /* Test call_rcu() invocation from interrupt handler. */
1329         if (cur_ops->call) {
1330                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1331
1332                 if (rhp)
1333                         cur_ops->call(rhp, rcu_torture_timer_cb);
1334         }
1335 }
1336
1337 /*
1338  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1339  * incrementing the corresponding element of the pipeline array.  The
1340  * counter in the element should never be greater than 1, otherwise, the
1341  * RCU implementation is broken.
1342  */
1343 static int
1344 rcu_torture_reader(void *arg)
1345 {
1346         unsigned long lastsleep = jiffies;
1347         long myid = (long)arg;
1348         int mynumonline = myid;
1349         DEFINE_TORTURE_RANDOM(rand);
1350         struct timer_list t;
1351
1352         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1353         set_user_nice(current, MAX_NICE);
1354         if (irqreader && cur_ops->irq_capable)
1355                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1356
1357         do {
1358                 if (irqreader && cur_ops->irq_capable) {
1359                         if (!timer_pending(&t))
1360                                 mod_timer(&t, jiffies + 1);
1361                 }
1362                 if (!rcu_torture_one_read(&rand))
1363                         schedule_timeout_interruptible(HZ);
1364                 if (time_after(jiffies, lastsleep)) {
1365                         schedule_timeout_interruptible(1);
1366                         lastsleep = jiffies + 10;
1367                 }
1368                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1369                         schedule_timeout_interruptible(HZ / 5);
1370                 stutter_wait("rcu_torture_reader");
1371         } while (!torture_must_stop());
1372         if (irqreader && cur_ops->irq_capable) {
1373                 del_timer_sync(&t);
1374                 destroy_timer_on_stack(&t);
1375         }
1376         torture_kthread_stopping("rcu_torture_reader");
1377         return 0;
1378 }
1379
1380 /*
1381  * Print torture statistics.  Caller must ensure that there is only
1382  * one call to this function at a given time!!!  This is normally
1383  * accomplished by relying on the module system to only have one copy
1384  * of the module loaded, and then by giving the rcu_torture_stats
1385  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1386  * thread is not running).
1387  */
1388 static void
1389 rcu_torture_stats_print(void)
1390 {
1391         int cpu;
1392         int i;
1393         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1394         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1395         static unsigned long rtcv_snap = ULONG_MAX;
1396         static bool splatted;
1397         struct task_struct *wtp;
1398
1399         for_each_possible_cpu(cpu) {
1400                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1401                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1402                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1403                 }
1404         }
1405         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1406                 if (pipesummary[i] != 0)
1407                         break;
1408         }
1409
1410         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1411         pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1412                 rcu_torture_current,
1413                 rcu_torture_current ? "ver" : "VER",
1414                 rcu_torture_current_version,
1415                 list_empty(&rcu_torture_freelist),
1416                 atomic_read(&n_rcu_torture_alloc),
1417                 atomic_read(&n_rcu_torture_alloc_fail),
1418                 atomic_read(&n_rcu_torture_free));
1419         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1420                 atomic_read(&n_rcu_torture_mberror),
1421                 n_rcu_torture_barrier_error,
1422                 n_rcu_torture_boost_ktrerror,
1423                 n_rcu_torture_boost_rterror);
1424         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1425                 n_rcu_torture_boost_failure,
1426                 n_rcu_torture_boosts,
1427                 atomic_long_read(&n_rcu_torture_timers));
1428         torture_onoff_stats();
1429         pr_cont("barrier: %ld/%ld:%ld\n",
1430                 n_barrier_successes,
1431                 n_barrier_attempts,
1432                 n_rcu_torture_barrier_error);
1433
1434         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1435         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1436             n_rcu_torture_barrier_error != 0 ||
1437             n_rcu_torture_boost_ktrerror != 0 ||
1438             n_rcu_torture_boost_rterror != 0 ||
1439             n_rcu_torture_boost_failure != 0 ||
1440             i > 1) {
1441                 pr_cont("%s", "!!! ");
1442                 atomic_inc(&n_rcu_torture_error);
1443                 WARN_ON_ONCE(1);
1444         }
1445         pr_cont("Reader Pipe: ");
1446         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1447                 pr_cont(" %ld", pipesummary[i]);
1448         pr_cont("\n");
1449
1450         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1451         pr_cont("Reader Batch: ");
1452         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1453                 pr_cont(" %ld", batchsummary[i]);
1454         pr_cont("\n");
1455
1456         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1457         pr_cont("Free-Block Circulation: ");
1458         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1459                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1460         }
1461         pr_cont("\n");
1462
1463         if (cur_ops->stats)
1464                 cur_ops->stats();
1465         if (rtcv_snap == rcu_torture_current_version &&
1466             rcu_torture_current != NULL) {
1467                 int __maybe_unused flags = 0;
1468                 unsigned long __maybe_unused gp_seq = 0;
1469
1470                 rcutorture_get_gp_data(cur_ops->ttype,
1471                                        &flags, &gp_seq);
1472                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1473                                         &flags, &gp_seq);
1474                 wtp = READ_ONCE(writer_task);
1475                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1476                          rcu_torture_writer_state_getname(),
1477                          rcu_torture_writer_state, gp_seq, flags,
1478                          wtp == NULL ? ~0UL : wtp->state,
1479                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1480                 if (!splatted && wtp) {
1481                         sched_show_task(wtp);
1482                         splatted = true;
1483                 }
1484                 show_rcu_gp_kthreads();
1485                 rcu_ftrace_dump(DUMP_ALL);
1486         }
1487         rtcv_snap = rcu_torture_current_version;
1488 }
1489
1490 /*
1491  * Periodically prints torture statistics, if periodic statistics printing
1492  * was specified via the stat_interval module parameter.
1493  */
1494 static int
1495 rcu_torture_stats(void *arg)
1496 {
1497         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1498         do {
1499                 schedule_timeout_interruptible(stat_interval * HZ);
1500                 rcu_torture_stats_print();
1501                 torture_shutdown_absorb("rcu_torture_stats");
1502         } while (!torture_must_stop());
1503         torture_kthread_stopping("rcu_torture_stats");
1504         return 0;
1505 }
1506
1507 static void
1508 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1509 {
1510         pr_alert("%s" TORTURE_FLAG
1511                  "--- %s: nreaders=%d nfakewriters=%d "
1512                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1513                  "shuffle_interval=%d stutter=%d irqreader=%d "
1514                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1515                  "test_boost=%d/%d test_boost_interval=%d "
1516                  "test_boost_duration=%d shutdown_secs=%d "
1517                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1518                  "n_barrier_cbs=%d "
1519                  "onoff_interval=%d onoff_holdoff=%d\n",
1520                  torture_type, tag, nrealreaders, nfakewriters,
1521                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1522                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1523                  test_boost, cur_ops->can_boost,
1524                  test_boost_interval, test_boost_duration, shutdown_secs,
1525                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1526                  n_barrier_cbs,
1527                  onoff_interval, onoff_holdoff);
1528 }
1529
1530 static int rcutorture_booster_cleanup(unsigned int cpu)
1531 {
1532         struct task_struct *t;
1533
1534         if (boost_tasks[cpu] == NULL)
1535                 return 0;
1536         mutex_lock(&boost_mutex);
1537         t = boost_tasks[cpu];
1538         boost_tasks[cpu] = NULL;
1539         rcu_torture_enable_rt_throttle();
1540         mutex_unlock(&boost_mutex);
1541
1542         /* This must be outside of the mutex, otherwise deadlock! */
1543         torture_stop_kthread(rcu_torture_boost, t);
1544         return 0;
1545 }
1546
1547 static int rcutorture_booster_init(unsigned int cpu)
1548 {
1549         int retval;
1550
1551         if (boost_tasks[cpu] != NULL)
1552                 return 0;  /* Already created, nothing more to do. */
1553
1554         /* Don't allow time recalculation while creating a new task. */
1555         mutex_lock(&boost_mutex);
1556         rcu_torture_disable_rt_throttle();
1557         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1558         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1559                                                   cpu_to_node(cpu),
1560                                                   "rcu_torture_boost");
1561         if (IS_ERR(boost_tasks[cpu])) {
1562                 retval = PTR_ERR(boost_tasks[cpu]);
1563                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1564                 n_rcu_torture_boost_ktrerror++;
1565                 boost_tasks[cpu] = NULL;
1566                 mutex_unlock(&boost_mutex);
1567                 return retval;
1568         }
1569         kthread_bind(boost_tasks[cpu], cpu);
1570         wake_up_process(boost_tasks[cpu]);
1571         mutex_unlock(&boost_mutex);
1572         return 0;
1573 }
1574
1575 /*
1576  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1577  * induces a CPU stall for the time specified by stall_cpu.
1578  */
1579 static int rcu_torture_stall(void *args)
1580 {
1581         unsigned long stop_at;
1582
1583         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1584         if (stall_cpu_holdoff > 0) {
1585                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1586                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1587                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1588         }
1589         if (!kthread_should_stop()) {
1590                 stop_at = ktime_get_seconds() + stall_cpu;
1591                 /* RCU CPU stall is expected behavior in following code. */
1592                 rcu_read_lock();
1593                 if (stall_cpu_irqsoff)
1594                         local_irq_disable();
1595                 else
1596                         preempt_disable();
1597                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1598                          smp_processor_id());
1599                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1600                                     stop_at))
1601                         continue;  /* Induce RCU CPU stall warning. */
1602                 if (stall_cpu_irqsoff)
1603                         local_irq_enable();
1604                 else
1605                         preempt_enable();
1606                 rcu_read_unlock();
1607                 pr_alert("rcu_torture_stall end.\n");
1608         }
1609         torture_shutdown_absorb("rcu_torture_stall");
1610         while (!kthread_should_stop())
1611                 schedule_timeout_interruptible(10 * HZ);
1612         return 0;
1613 }
1614
1615 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1616 static int __init rcu_torture_stall_init(void)
1617 {
1618         if (stall_cpu <= 0)
1619                 return 0;
1620         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1621 }
1622
1623 /* State structure for forward-progress self-propagating RCU callback. */
1624 struct fwd_cb_state {
1625         struct rcu_head rh;
1626         int stop;
1627 };
1628
1629 /*
1630  * Forward-progress self-propagating RCU callback function.  Because
1631  * callbacks run from softirq, this function is an implicit RCU read-side
1632  * critical section.
1633  */
1634 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1635 {
1636         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1637
1638         if (READ_ONCE(fcsp->stop)) {
1639                 WRITE_ONCE(fcsp->stop, 2);
1640                 return;
1641         }
1642         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1643 }
1644
1645 /* State for continuous-flood RCU callbacks. */
1646 struct rcu_fwd_cb {
1647         struct rcu_head rh;
1648         struct rcu_fwd_cb *rfc_next;
1649         int rfc_gps;
1650 };
1651 static DEFINE_SPINLOCK(rcu_fwd_lock);
1652 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1653 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1654 static long n_launders_cb;
1655 static unsigned long rcu_fwd_startat;
1656 static bool rcu_fwd_emergency_stop;
1657 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1658 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1659 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1660 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1661 struct rcu_launder_hist {
1662         long n_launders;
1663         unsigned long launder_gp_seq;
1664 };
1665 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1666 static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1667 static unsigned long rcu_launder_gp_seq_start;
1668
1669 static void rcu_torture_fwd_cb_hist(void)
1670 {
1671         unsigned long gps;
1672         unsigned long gps_old;
1673         int i;
1674         int j;
1675
1676         for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1677                 if (n_launders_hist[i].n_launders > 0)
1678                         break;
1679         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1680                  __func__, jiffies - rcu_fwd_startat);
1681         gps_old = rcu_launder_gp_seq_start;
1682         for (j = 0; j <= i; j++) {
1683                 gps = n_launders_hist[j].launder_gp_seq;
1684                 pr_cont(" %ds/%d: %ld:%ld",
1685                         j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1686                         rcutorture_seq_diff(gps, gps_old));
1687                 gps_old = gps;
1688         }
1689         pr_cont("\n");
1690 }
1691
1692 /* Callback function for continuous-flood RCU callbacks. */
1693 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1694 {
1695         unsigned long flags;
1696         int i;
1697         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1698         struct rcu_fwd_cb **rfcpp;
1699
1700         rfcp->rfc_next = NULL;
1701         rfcp->rfc_gps++;
1702         spin_lock_irqsave(&rcu_fwd_lock, flags);
1703         rfcpp = rcu_fwd_cb_tail;
1704         rcu_fwd_cb_tail = &rfcp->rfc_next;
1705         WRITE_ONCE(*rfcpp, rfcp);
1706         WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1707         i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1708         if (i >= ARRAY_SIZE(n_launders_hist))
1709                 i = ARRAY_SIZE(n_launders_hist) - 1;
1710         n_launders_hist[i].n_launders++;
1711         n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1712         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1713 }
1714
1715 // Give the scheduler a chance, even on nohz_full CPUs.
1716 static void rcu_torture_fwd_prog_cond_resched(void)
1717 {
1718         if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
1719                 if (need_resched())
1720                         schedule();
1721         } else {
1722                 cond_resched();
1723         }
1724 }
1725
1726 /*
1727  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1728  * test is over or because we hit an OOM event.
1729  */
1730 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1731 {
1732         unsigned long flags;
1733         unsigned long freed = 0;
1734         struct rcu_fwd_cb *rfcp;
1735
1736         for (;;) {
1737                 spin_lock_irqsave(&rcu_fwd_lock, flags);
1738                 rfcp = rcu_fwd_cb_head;
1739                 if (!rfcp) {
1740                         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1741                         break;
1742                 }
1743                 rcu_fwd_cb_head = rfcp->rfc_next;
1744                 if (!rcu_fwd_cb_head)
1745                         rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1746                 spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1747                 kfree(rfcp);
1748                 freed++;
1749                 rcu_torture_fwd_prog_cond_resched();
1750         }
1751         return freed;
1752 }
1753
1754 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1755 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1756 {
1757         unsigned long cver;
1758         unsigned long dur;
1759         struct fwd_cb_state fcs;
1760         unsigned long gps;
1761         int idx;
1762         int sd;
1763         int sd4;
1764         bool selfpropcb = false;
1765         unsigned long stopat;
1766         static DEFINE_TORTURE_RANDOM(trs);
1767
1768         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1769                 init_rcu_head_on_stack(&fcs.rh);
1770                 selfpropcb = true;
1771         }
1772
1773         /* Tight loop containing cond_resched(). */
1774         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1775         cur_ops->sync(); /* Later readers see above write. */
1776         if  (selfpropcb) {
1777                 WRITE_ONCE(fcs.stop, 0);
1778                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1779         }
1780         cver = READ_ONCE(rcu_torture_current_version);
1781         gps = cur_ops->get_gp_seq();
1782         sd = cur_ops->stall_dur() + 1;
1783         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1784         dur = sd4 + torture_random(&trs) % (sd - sd4);
1785         WRITE_ONCE(rcu_fwd_startat, jiffies);
1786         stopat = rcu_fwd_startat + dur;
1787         while (time_before(jiffies, stopat) &&
1788                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1789                 idx = cur_ops->readlock();
1790                 udelay(10);
1791                 cur_ops->readunlock(idx);
1792                 if (!fwd_progress_need_resched || need_resched())
1793                         rcu_torture_fwd_prog_cond_resched();
1794         }
1795         (*tested_tries)++;
1796         if (!time_before(jiffies, stopat) &&
1797             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1798                 (*tested)++;
1799                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1800                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1801                 WARN_ON(!cver && gps < 2);
1802                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1803         }
1804         if (selfpropcb) {
1805                 WRITE_ONCE(fcs.stop, 1);
1806                 cur_ops->sync(); /* Wait for running CB to complete. */
1807                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1808         }
1809
1810         if (selfpropcb) {
1811                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1812                 destroy_rcu_head_on_stack(&fcs.rh);
1813         }
1814         schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
1815         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1816 }
1817
1818 /* Carry out call_rcu() forward-progress testing. */
1819 static void rcu_torture_fwd_prog_cr(void)
1820 {
1821         unsigned long cver;
1822         unsigned long gps;
1823         int i;
1824         long n_launders;
1825         long n_launders_cb_snap;
1826         long n_launders_sa;
1827         long n_max_cbs;
1828         long n_max_gps;
1829         struct rcu_fwd_cb *rfcp;
1830         struct rcu_fwd_cb *rfcpn;
1831         unsigned long stopat;
1832         unsigned long stoppedat;
1833
1834         if (READ_ONCE(rcu_fwd_emergency_stop))
1835                 return; /* Get out of the way quickly, no GP wait! */
1836         if (!cur_ops->call)
1837                 return; /* Can't do call_rcu() fwd prog without ->call. */
1838
1839         /* Loop continuously posting RCU callbacks. */
1840         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1841         cur_ops->sync(); /* Later readers see above write. */
1842         WRITE_ONCE(rcu_fwd_startat, jiffies);
1843         stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1844         n_launders = 0;
1845         n_launders_cb = 0;
1846         n_launders_sa = 0;
1847         n_max_cbs = 0;
1848         n_max_gps = 0;
1849         for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1850                 n_launders_hist[i].n_launders = 0;
1851         cver = READ_ONCE(rcu_torture_current_version);
1852         gps = cur_ops->get_gp_seq();
1853         rcu_launder_gp_seq_start = gps;
1854         while (time_before(jiffies, stopat) &&
1855                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1856                 rfcp = READ_ONCE(rcu_fwd_cb_head);
1857                 rfcpn = NULL;
1858                 if (rfcp)
1859                         rfcpn = READ_ONCE(rfcp->rfc_next);
1860                 if (rfcpn) {
1861                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1862                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1863                                 break;
1864                         rcu_fwd_cb_head = rfcpn;
1865                         n_launders++;
1866                         n_launders_sa++;
1867                 } else {
1868                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1869                         if (WARN_ON_ONCE(!rfcp)) {
1870                                 schedule_timeout_interruptible(1);
1871                                 continue;
1872                         }
1873                         n_max_cbs++;
1874                         n_launders_sa = 0;
1875                         rfcp->rfc_gps = 0;
1876                 }
1877                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1878                 rcu_torture_fwd_prog_cond_resched();
1879         }
1880         stoppedat = jiffies;
1881         n_launders_cb_snap = READ_ONCE(n_launders_cb);
1882         cver = READ_ONCE(rcu_torture_current_version) - cver;
1883         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1884         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1885         (void)rcu_torture_fwd_prog_cbfree();
1886
1887         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
1888                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1889                 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",
1890                          __func__,
1891                          stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1892                          n_launders + n_max_cbs - n_launders_cb_snap,
1893                          n_launders, n_launders_sa,
1894                          n_max_gps, n_max_cbs, cver, gps);
1895                 rcu_torture_fwd_cb_hist();
1896         }
1897         schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
1898         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1899 }
1900
1901
1902 /*
1903  * OOM notifier, but this only prints diagnostic information for the
1904  * current forward-progress test.
1905  */
1906 static int rcutorture_oom_notify(struct notifier_block *self,
1907                                  unsigned long notused, void *nfreed)
1908 {
1909         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1910              __func__);
1911         rcu_torture_fwd_cb_hist();
1912         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
1913         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1914         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1915         pr_info("%s: Freed %lu RCU callbacks.\n",
1916                 __func__, rcu_torture_fwd_prog_cbfree());
1917         rcu_barrier();
1918         pr_info("%s: Freed %lu RCU callbacks.\n",
1919                 __func__, rcu_torture_fwd_prog_cbfree());
1920         rcu_barrier();
1921         pr_info("%s: Freed %lu RCU callbacks.\n",
1922                 __func__, rcu_torture_fwd_prog_cbfree());
1923         smp_mb(); /* Frees before return to avoid redoing OOM. */
1924         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1925         pr_info("%s returning after OOM processing.\n", __func__);
1926         return NOTIFY_OK;
1927 }
1928
1929 static struct notifier_block rcutorture_oom_nb = {
1930         .notifier_call = rcutorture_oom_notify
1931 };
1932
1933 /* Carry out grace-period forward-progress testing. */
1934 static int rcu_torture_fwd_prog(void *args)
1935 {
1936         int tested = 0;
1937         int tested_tries = 0;
1938
1939         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1940         rcu_bind_current_to_nocb();
1941         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1942                 set_user_nice(current, MAX_NICE);
1943         do {
1944                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1945                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
1946                 register_oom_notifier(&rcutorture_oom_nb);
1947                 rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1948                 rcu_torture_fwd_prog_cr();
1949                 unregister_oom_notifier(&rcutorture_oom_nb);
1950
1951                 /* Avoid slow periods, better to test when busy. */
1952                 stutter_wait("rcu_torture_fwd_prog");
1953         } while (!torture_must_stop());
1954         /* Short runs might not contain a valid forward-progress attempt. */
1955         WARN_ON(!tested && tested_tries >= 5);
1956         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1957         torture_kthread_stopping("rcu_torture_fwd_prog");
1958         return 0;
1959 }
1960
1961 /* If forward-progress checking is requested and feasible, spawn the thread. */
1962 static int __init rcu_torture_fwd_prog_init(void)
1963 {
1964         if (!fwd_progress)
1965                 return 0; /* Not requested, so don't do it. */
1966         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1967             cur_ops == &rcu_busted_ops) {
1968                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1969                 return 0;
1970         }
1971         if (stall_cpu > 0) {
1972                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1973                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1974                         return -EINVAL; /* In module, can fail back to user. */
1975                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1976                 return 0;
1977         }
1978         if (fwd_progress_holdoff <= 0)
1979                 fwd_progress_holdoff = 1;
1980         if (fwd_progress_div <= 0)
1981                 fwd_progress_div = 4;
1982         return torture_create_kthread(rcu_torture_fwd_prog,
1983                                       NULL, fwd_prog_task);
1984 }
1985
1986 /* Callback function for RCU barrier testing. */
1987 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1988 {
1989         atomic_inc(&barrier_cbs_invoked);
1990 }
1991
1992 /* kthread function to register callbacks used to test RCU barriers. */
1993 static int rcu_torture_barrier_cbs(void *arg)
1994 {
1995         long myid = (long)arg;
1996         bool lastphase = 0;
1997         bool newphase;
1998         struct rcu_head rcu;
1999
2000         init_rcu_head_on_stack(&rcu);
2001         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2002         set_user_nice(current, MAX_NICE);
2003         do {
2004                 wait_event(barrier_cbs_wq[myid],
2005                            (newphase =
2006                             smp_load_acquire(&barrier_phase)) != lastphase ||
2007                            torture_must_stop());
2008                 lastphase = newphase;
2009                 if (torture_must_stop())
2010                         break;
2011                 /*
2012                  * The above smp_load_acquire() ensures barrier_phase load
2013                  * is ordered before the following ->call().
2014                  */
2015                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
2016                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2017                 local_irq_enable();
2018                 if (atomic_dec_and_test(&barrier_cbs_count))
2019                         wake_up(&barrier_wq);
2020         } while (!torture_must_stop());
2021         if (cur_ops->cb_barrier != NULL)
2022                 cur_ops->cb_barrier();
2023         destroy_rcu_head_on_stack(&rcu);
2024         torture_kthread_stopping("rcu_torture_barrier_cbs");
2025         return 0;
2026 }
2027
2028 /* kthread function to drive and coordinate RCU barrier testing. */
2029 static int rcu_torture_barrier(void *arg)
2030 {
2031         int i;
2032
2033         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2034         do {
2035                 atomic_set(&barrier_cbs_invoked, 0);
2036                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
2037                 /* Ensure barrier_phase ordered after prior assignments. */
2038                 smp_store_release(&barrier_phase, !barrier_phase);
2039                 for (i = 0; i < n_barrier_cbs; i++)
2040                         wake_up(&barrier_cbs_wq[i]);
2041                 wait_event(barrier_wq,
2042                            atomic_read(&barrier_cbs_count) == 0 ||
2043                            torture_must_stop());
2044                 if (torture_must_stop())
2045                         break;
2046                 n_barrier_attempts++;
2047                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2048                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2049                         n_rcu_torture_barrier_error++;
2050                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2051                                atomic_read(&barrier_cbs_invoked),
2052                                n_barrier_cbs);
2053                         WARN_ON_ONCE(1);
2054                 } else {
2055                         n_barrier_successes++;
2056                 }
2057                 schedule_timeout_interruptible(HZ / 10);
2058         } while (!torture_must_stop());
2059         torture_kthread_stopping("rcu_torture_barrier");
2060         return 0;
2061 }
2062
2063 /* Initialize RCU barrier testing. */
2064 static int rcu_torture_barrier_init(void)
2065 {
2066         int i;
2067         int ret;
2068
2069         if (n_barrier_cbs <= 0)
2070                 return 0;
2071         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2072                 pr_alert("%s" TORTURE_FLAG
2073                          " Call or barrier ops missing for %s,\n",
2074                          torture_type, cur_ops->name);
2075                 pr_alert("%s" TORTURE_FLAG
2076                          " RCU barrier testing omitted from run.\n",
2077                          torture_type);
2078                 return 0;
2079         }
2080         atomic_set(&barrier_cbs_count, 0);
2081         atomic_set(&barrier_cbs_invoked, 0);
2082         barrier_cbs_tasks =
2083                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2084                         GFP_KERNEL);
2085         barrier_cbs_wq =
2086                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2087         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2088                 return -ENOMEM;
2089         for (i = 0; i < n_barrier_cbs; i++) {
2090                 init_waitqueue_head(&barrier_cbs_wq[i]);
2091                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2092                                              (void *)(long)i,
2093                                              barrier_cbs_tasks[i]);
2094                 if (ret)
2095                         return ret;
2096         }
2097         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2098 }
2099
2100 /* Clean up after RCU barrier testing. */
2101 static void rcu_torture_barrier_cleanup(void)
2102 {
2103         int i;
2104
2105         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2106         if (barrier_cbs_tasks != NULL) {
2107                 for (i = 0; i < n_barrier_cbs; i++)
2108                         torture_stop_kthread(rcu_torture_barrier_cbs,
2109                                              barrier_cbs_tasks[i]);
2110                 kfree(barrier_cbs_tasks);
2111                 barrier_cbs_tasks = NULL;
2112         }
2113         if (barrier_cbs_wq != NULL) {
2114                 kfree(barrier_cbs_wq);
2115                 barrier_cbs_wq = NULL;
2116         }
2117 }
2118
2119 static bool rcu_torture_can_boost(void)
2120 {
2121         static int boost_warn_once;
2122         int prio;
2123
2124         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2125                 return false;
2126
2127         prio = rcu_get_gp_kthreads_prio();
2128         if (!prio)
2129                 return false;
2130
2131         if (prio < 2) {
2132                 if (boost_warn_once  == 1)
2133                         return false;
2134
2135                 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);
2136                 boost_warn_once = 1;
2137                 return false;
2138         }
2139
2140         return true;
2141 }
2142
2143 static enum cpuhp_state rcutor_hp;
2144
2145 static void
2146 rcu_torture_cleanup(void)
2147 {
2148         int firsttime;
2149         int flags = 0;
2150         unsigned long gp_seq = 0;
2151         int i;
2152
2153         if (torture_cleanup_begin()) {
2154                 if (cur_ops->cb_barrier != NULL)
2155                         cur_ops->cb_barrier();
2156                 return;
2157         }
2158         if (!cur_ops) {
2159                 torture_cleanup_end();
2160                 return;
2161         }
2162
2163         rcu_torture_barrier_cleanup();
2164         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2165         torture_stop_kthread(rcu_torture_stall, stall_task);
2166         torture_stop_kthread(rcu_torture_writer, writer_task);
2167
2168         if (reader_tasks) {
2169                 for (i = 0; i < nrealreaders; i++)
2170                         torture_stop_kthread(rcu_torture_reader,
2171                                              reader_tasks[i]);
2172                 kfree(reader_tasks);
2173         }
2174         rcu_torture_current = NULL;
2175
2176         if (fakewriter_tasks) {
2177                 for (i = 0; i < nfakewriters; i++) {
2178                         torture_stop_kthread(rcu_torture_fakewriter,
2179                                              fakewriter_tasks[i]);
2180                 }
2181                 kfree(fakewriter_tasks);
2182                 fakewriter_tasks = NULL;
2183         }
2184
2185         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2186         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2187         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2188                  cur_ops->name, gp_seq, flags);
2189         torture_stop_kthread(rcu_torture_stats, stats_task);
2190         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2191         if (rcu_torture_can_boost())
2192                 cpuhp_remove_state(rcutor_hp);
2193
2194         /*
2195          * Wait for all RCU callbacks to fire, then do torture-type-specific
2196          * cleanup operations.
2197          */
2198         if (cur_ops->cb_barrier != NULL)
2199                 cur_ops->cb_barrier();
2200         if (cur_ops->cleanup != NULL)
2201                 cur_ops->cleanup();
2202
2203         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2204
2205         if (err_segs_recorded) {
2206                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2207                 if (rt_read_nsegs == 0)
2208                         pr_alert("\t: No segments recorded!!!\n");
2209                 firsttime = 1;
2210                 for (i = 0; i < rt_read_nsegs; i++) {
2211                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2212                         if (err_segs[i].rt_delay_jiffies != 0) {
2213                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2214                                         err_segs[i].rt_delay_jiffies);
2215                                 firsttime = 0;
2216                         }
2217                         if (err_segs[i].rt_delay_ms != 0) {
2218                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2219                                         err_segs[i].rt_delay_ms);
2220                                 firsttime = 0;
2221                         }
2222                         if (err_segs[i].rt_delay_us != 0) {
2223                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2224                                         err_segs[i].rt_delay_us);
2225                                 firsttime = 0;
2226                         }
2227                         pr_cont("%s\n",
2228                                 err_segs[i].rt_preempted ? "preempted" : "");
2229
2230                 }
2231         }
2232         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2233                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2234         else if (torture_onoff_failures())
2235                 rcu_torture_print_module_parms(cur_ops,
2236                                                "End of test: RCU_HOTPLUG");
2237         else
2238                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2239         torture_cleanup_end();
2240 }
2241
2242 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2243 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2244 {
2245 }
2246
2247 static void rcu_torture_err_cb(struct rcu_head *rhp)
2248 {
2249         /*
2250          * This -might- happen due to race conditions, but is unlikely.
2251          * The scenario that leads to this happening is that the
2252          * first of the pair of duplicate callbacks is queued,
2253          * someone else starts a grace period that includes that
2254          * callback, then the second of the pair must wait for the
2255          * next grace period.  Unlikely, but can happen.  If it
2256          * does happen, the debug-objects subsystem won't have splatted.
2257          */
2258         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2259 }
2260 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2261
2262 /*
2263  * Verify that double-free causes debug-objects to complain, but only
2264  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2265  * cannot be carried out.
2266  */
2267 static void rcu_test_debug_objects(void)
2268 {
2269 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2270         struct rcu_head rh1;
2271         struct rcu_head rh2;
2272
2273         init_rcu_head_on_stack(&rh1);
2274         init_rcu_head_on_stack(&rh2);
2275         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2276
2277         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2278         preempt_disable(); /* Prevent preemption from interrupting test. */
2279         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2280         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2281         local_irq_disable(); /* Make it harder to start a new grace period. */
2282         call_rcu(&rh2, rcu_torture_leak_cb);
2283         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2284         local_irq_enable();
2285         rcu_read_unlock();
2286         preempt_enable();
2287
2288         /* Wait for them all to get done so we can safely return. */
2289         rcu_barrier();
2290         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2291         destroy_rcu_head_on_stack(&rh1);
2292         destroy_rcu_head_on_stack(&rh2);
2293 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2294         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2295 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2296 }
2297
2298 static void rcutorture_sync(void)
2299 {
2300         static unsigned long n;
2301
2302         if (cur_ops->sync && !(++n & 0xfff))
2303                 cur_ops->sync();
2304 }
2305
2306 static int __init
2307 rcu_torture_init(void)
2308 {
2309         long i;
2310         int cpu;
2311         int firsterr = 0;
2312         static struct rcu_torture_ops *torture_ops[] = {
2313                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2314                 &busted_srcud_ops, &tasks_ops, &trivial_ops,
2315         };
2316
2317         if (!torture_init_begin(torture_type, verbose))
2318                 return -EBUSY;
2319
2320         /* Process args and tell the world that the torturer is on the job. */
2321         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2322                 cur_ops = torture_ops[i];
2323                 if (strcmp(torture_type, cur_ops->name) == 0)
2324                         break;
2325         }
2326         if (i == ARRAY_SIZE(torture_ops)) {
2327                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2328                          torture_type);
2329                 pr_alert("rcu-torture types:");
2330                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2331                         pr_cont(" %s", torture_ops[i]->name);
2332                 pr_cont("\n");
2333                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2334                 firsterr = -EINVAL;
2335                 cur_ops = NULL;
2336                 goto unwind;
2337         }
2338         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2339                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2340                 fqs_duration = 0;
2341         }
2342         if (cur_ops->init)
2343                 cur_ops->init();
2344
2345         if (nreaders >= 0) {
2346                 nrealreaders = nreaders;
2347         } else {
2348                 nrealreaders = num_online_cpus() - 2 - nreaders;
2349                 if (nrealreaders <= 0)
2350                         nrealreaders = 1;
2351         }
2352         rcu_torture_print_module_parms(cur_ops, "Start of test");
2353
2354         /* Set up the freelist. */
2355
2356         INIT_LIST_HEAD(&rcu_torture_freelist);
2357         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2358                 rcu_tortures[i].rtort_mbtest = 0;
2359                 list_add_tail(&rcu_tortures[i].rtort_free,
2360                               &rcu_torture_freelist);
2361         }
2362
2363         /* Initialize the statistics so that each run gets its own numbers. */
2364
2365         rcu_torture_current = NULL;
2366         rcu_torture_current_version = 0;
2367         atomic_set(&n_rcu_torture_alloc, 0);
2368         atomic_set(&n_rcu_torture_alloc_fail, 0);
2369         atomic_set(&n_rcu_torture_free, 0);
2370         atomic_set(&n_rcu_torture_mberror, 0);
2371         atomic_set(&n_rcu_torture_error, 0);
2372         n_rcu_torture_barrier_error = 0;
2373         n_rcu_torture_boost_ktrerror = 0;
2374         n_rcu_torture_boost_rterror = 0;
2375         n_rcu_torture_boost_failure = 0;
2376         n_rcu_torture_boosts = 0;
2377         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2378                 atomic_set(&rcu_torture_wcount[i], 0);
2379         for_each_possible_cpu(cpu) {
2380                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2381                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2382                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2383                 }
2384         }
2385         err_segs_recorded = 0;
2386         rt_read_nsegs = 0;
2387
2388         /* Start up the kthreads. */
2389
2390         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2391                                           writer_task);
2392         if (firsterr)
2393                 goto unwind;
2394         if (nfakewriters > 0) {
2395                 fakewriter_tasks = kcalloc(nfakewriters,
2396                                            sizeof(fakewriter_tasks[0]),
2397                                            GFP_KERNEL);
2398                 if (fakewriter_tasks == NULL) {
2399                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2400                         firsterr = -ENOMEM;
2401                         goto unwind;
2402                 }
2403         }
2404         for (i = 0; i < nfakewriters; i++) {
2405                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2406                                                   NULL, fakewriter_tasks[i]);
2407                 if (firsterr)
2408                         goto unwind;
2409         }
2410         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2411                                GFP_KERNEL);
2412         if (reader_tasks == NULL) {
2413                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2414                 firsterr = -ENOMEM;
2415                 goto unwind;
2416         }
2417         for (i = 0; i < nrealreaders; i++) {
2418                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2419                                                   reader_tasks[i]);
2420                 if (firsterr)
2421                         goto unwind;
2422         }
2423         if (stat_interval > 0) {
2424                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2425                                                   stats_task);
2426                 if (firsterr)
2427                         goto unwind;
2428         }
2429         if (test_no_idle_hz && shuffle_interval > 0) {
2430                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2431                 if (firsterr)
2432                         goto unwind;
2433         }
2434         if (stutter < 0)
2435                 stutter = 0;
2436         if (stutter) {
2437                 int t;
2438
2439                 t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
2440                 firsterr = torture_stutter_init(stutter * HZ, t);
2441                 if (firsterr)
2442                         goto unwind;
2443         }
2444         if (fqs_duration < 0)
2445                 fqs_duration = 0;
2446         if (fqs_duration) {
2447                 /* Create the fqs thread */
2448                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2449                                                   fqs_task);
2450                 if (firsterr)
2451                         goto unwind;
2452         }
2453         if (test_boost_interval < 1)
2454                 test_boost_interval = 1;
2455         if (test_boost_duration < 2)
2456                 test_boost_duration = 2;
2457         if (rcu_torture_can_boost()) {
2458
2459                 boost_starttime = jiffies + test_boost_interval * HZ;
2460
2461                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2462                                              rcutorture_booster_init,
2463                                              rcutorture_booster_cleanup);
2464                 if (firsterr < 0)
2465                         goto unwind;
2466                 rcutor_hp = firsterr;
2467         }
2468         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2469         if (firsterr)
2470                 goto unwind;
2471         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2472                                       rcutorture_sync);
2473         if (firsterr)
2474                 goto unwind;
2475         firsterr = rcu_torture_stall_init();
2476         if (firsterr)
2477                 goto unwind;
2478         firsterr = rcu_torture_fwd_prog_init();
2479         if (firsterr)
2480                 goto unwind;
2481         firsterr = rcu_torture_barrier_init();
2482         if (firsterr)
2483                 goto unwind;
2484         if (object_debug)
2485                 rcu_test_debug_objects();
2486         torture_init_end();
2487         return 0;
2488
2489 unwind:
2490         torture_init_end();
2491         rcu_torture_cleanup();
2492         return firsterr;
2493 }
2494
2495 module_init(rcu_torture_init);
2496 module_exit(rcu_torture_cleanup);