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 #include <linux/tick.h>
  48
  49 #include "rcu.h"
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  53
  54
  55 /* Bits for ->extendables field, extendables param, and related definitions. */
  56 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  57 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  58 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  59 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  60 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  61 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  62 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  63 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  64 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  65 #define RCUTORTURE_MAX_EXTEND    \
  66         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  67          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  68 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  69                                         /* Must be power of two minus one. */
  70 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  71
  72 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  73               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  74 torture_param(int, fqs_duration, 0,
  75               "Duration of fqs bursts (us), 0 to disable");
  76 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  77 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  78 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  79 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  80 torture_param(int, fwd_progress_holdoff, 60,
  81               "Time between forward-progress tests (s)");
  82 torture_param(bool, fwd_progress_need_resched, 1,
  83               "Hide cond_resched() behind need_resched()");
  84 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  85 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  86 torture_param(bool, gp_normal, false,
  87              "Use normal (non-expedited) GP wait primitives");
  88 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  89 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  90 torture_param(int, n_barrier_cbs, 0,
  91              "# of callbacks/kthreads for barrier testing");
  92 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  93 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  94 torture_param(int, object_debug, 0,
  95              "Enable debug-object double call_rcu() testing");
  96 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  97 torture_param(int, onoff_interval, 0,
  98              "Time between CPU hotplugs (jiffies), 0=disable");
  99 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 100 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 101 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 102 torture_param(int, stall_cpu_holdoff, 10,
 103              "Time to wait before starting stall (s).");
 104 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 105 torture_param(int, stat_interval, 60,
 106              "Number of seconds between stats printk()s");
 107 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 108 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 109 torture_param(int, test_boost_duration, 4,
 110              "Duration of each boost test, seconds.");
 111 torture_param(int, test_boost_interval, 7,
 112              "Interval between boost tests, seconds.");
 113 torture_param(bool, test_no_idle_hz, true,
 114              "Test support for tickless idle CPUs");
 115 torture_param(int, verbose, 1,
 116              "Enable verbose debugging printk()s");
 117
 118 static char *torture_type = "rcu";
 119 module_param(torture_type, charp, 0444);
 120 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 121
 122 static int nrealreaders;
 123 static struct task_struct *writer_task;
 124 static struct task_struct **fakewriter_tasks;
 125 static struct task_struct **reader_tasks;
 126 static struct task_struct *stats_task;
 127 static struct task_struct *fqs_task;
 128 static struct task_struct *boost_tasks[NR_CPUS];
 129 static struct task_struct *stall_task;
 130 static struct task_struct *fwd_prog_task;
 131 static struct task_struct **barrier_cbs_tasks;
 132 static struct task_struct *barrier_task;
 133
 134 #define RCU_TORTURE_PIPE_LEN 10
 135
 136 struct rcu_torture {
 137         struct rcu_head rtort_rcu;
 138         int rtort_pipe_count;
 139         struct list_head rtort_free;
 140         int rtort_mbtest;
 141 };
 142
 143 static LIST_HEAD(rcu_torture_freelist);
 144 static struct rcu_torture __rcu *rcu_torture_current;
 145 static unsigned long rcu_torture_current_version;
 146 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 147 static DEFINE_SPINLOCK(rcu_torture_lock);
 148 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 149 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 150 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 151 static atomic_t n_rcu_torture_alloc;
 152 static atomic_t n_rcu_torture_alloc_fail;
 153 static atomic_t n_rcu_torture_free;
 154 static atomic_t n_rcu_torture_mberror;
 155 static atomic_t n_rcu_torture_error;
 156 static long n_rcu_torture_barrier_error;
 157 static long n_rcu_torture_boost_ktrerror;
 158 static long n_rcu_torture_boost_rterror;
 159 static long n_rcu_torture_boost_failure;
 160 static long n_rcu_torture_boosts;
 161 static atomic_long_t n_rcu_torture_timers;
 162 static long n_barrier_attempts;
 163 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 164 static struct list_head rcu_torture_removed;
 165 static unsigned long shutdown_jiffies;
 166
 167 static int rcu_torture_writer_state;
 168 #define RTWS_FIXED_DELAY        0
 169 #define RTWS_DELAY              1
 170 #define RTWS_REPLACE            2
 171 #define RTWS_DEF_FREE           3
 172 #define RTWS_EXP_SYNC           4
 173 #define RTWS_COND_GET           5
 174 #define RTWS_COND_SYNC          6
 175 #define RTWS_SYNC               7
 176 #define RTWS_STUTTER            8
 177 #define RTWS_STOPPING           9
 178 static const char * const rcu_torture_writer_state_names[] = {
 179         "RTWS_FIXED_DELAY",
 180         "RTWS_DELAY",
 181         "RTWS_REPLACE",
 182         "RTWS_DEF_FREE",
 183         "RTWS_EXP_SYNC",
 184         "RTWS_COND_GET",
 185         "RTWS_COND_SYNC",
 186         "RTWS_SYNC",
 187         "RTWS_STUTTER",
 188         "RTWS_STOPPING",
 189 };
 190
 191 /* Record reader segment types and duration for first failing read. */
 192 struct rt_read_seg {
 193         int rt_readstate;
 194         unsigned long rt_delay_jiffies;
 195         unsigned long rt_delay_ms;
 196         unsigned long rt_delay_us;
 197         bool rt_preempted;
 198 };
 199 static int err_segs_recorded;
 200 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 201 static int rt_read_nsegs;
 202
 203 static const char *rcu_torture_writer_state_getname(void)
 204 {
 205         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 206
 207         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 208                 return "???";
 209         return rcu_torture_writer_state_names[i];
 210 }
 211
 212 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 213 #define rcu_can_boost() 1
 214 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 215 #define rcu_can_boost() 0
 216 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 217
 218 #ifdef CONFIG_RCU_TRACE
 219 static u64 notrace rcu_trace_clock_local(void)
 220 {
 221         u64 ts = trace_clock_local();
 222
 223         (void)do_div(ts, NSEC_PER_USEC);
 224         return ts;
 225 }
 226 #else /* #ifdef CONFIG_RCU_TRACE */
 227 static u64 notrace rcu_trace_clock_local(void)
 228 {
 229         return 0ULL;
 230 }
 231 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 232
 233 /*
 234  * Stop aggressive CPU-hog tests a bit before the end of the test in order
 235  * to avoid interfering with test shutdown.
 236  */
 237 static bool shutdown_time_arrived(void)
 238 {
 239         return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 240 }
 241
 242 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 243 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 244                                         /*  and boost task create/destroy. */
 245 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 246 static bool barrier_phase;              /* Test phase. */
 247 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 248 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 249 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 250
 251 static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 252
 253 /*
 254  * Allocate an element from the rcu_tortures pool.
 255  */
 256 static struct rcu_torture *
 257 rcu_torture_alloc(void)
 258 {
 259         struct list_head *p;
 260
 261         spin_lock_bh(&rcu_torture_lock);
 262         if (list_empty(&rcu_torture_freelist)) {
 263                 atomic_inc(&n_rcu_torture_alloc_fail);
 264                 spin_unlock_bh(&rcu_torture_lock);
 265                 return NULL;
 266         }
 267         atomic_inc(&n_rcu_torture_alloc);
 268         p = rcu_torture_freelist.next;
 269         list_del_init(p);
 270         spin_unlock_bh(&rcu_torture_lock);
 271         return container_of(p, struct rcu_torture, rtort_free);
 272 }
 273
 274 /*
 275  * Free an element to the rcu_tortures pool.
 276  */
 277 static void
 278 rcu_torture_free(struct rcu_torture *p)
 279 {
 280         atomic_inc(&n_rcu_torture_free);
 281         spin_lock_bh(&rcu_torture_lock);
 282         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 283         spin_unlock_bh(&rcu_torture_lock);
 284 }
 285
 286 /*
 287  * Operations vector for selecting different types of tests.
 288  */
 289
 290 struct rcu_torture_ops {
 291         int ttype;
 292         void (*init)(void);
 293         void (*cleanup)(void);
 294         int (*readlock)(void);
 295         void (*read_delay)(struct torture_random_state *rrsp,
 296                            struct rt_read_seg *rtrsp);
 297         void (*readunlock)(int idx);
 298         unsigned long (*get_gp_seq)(void);
 299         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 300         void (*deferred_free)(struct rcu_torture *p);
 301         void (*sync)(void);
 302         void (*exp_sync)(void);
 303         unsigned long (*get_state)(void);
 304         void (*cond_sync)(unsigned long oldstate);
 305         call_rcu_func_t call;
 306         void (*cb_barrier)(void);
 307         void (*fqs)(void);
 308         void (*stats)(void);
 309         int (*stall_dur)(void);
 310         int irq_capable;
 311         int can_boost;
 312         int extendables;
 313         int slow_gps;
 314         const char *name;
 315 };
 316
 317 static struct rcu_torture_ops *cur_ops;
 318
 319 /*
 320  * Definitions for rcu torture testing.
 321  */
 322
 323 static int rcu_torture_read_lock(void) __acquires(RCU)
 324 {
 325         rcu_read_lock();
 326         return 0;
 327 }
 328
 329 static void
 330 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 331 {
 332         unsigned long started;
 333         unsigned long completed;
 334         const unsigned long shortdelay_us = 200;
 335         unsigned long longdelay_ms = 300;
 336         unsigned long long ts;
 337
 338         /* We want a short delay sometimes to make a reader delay the grace
 339          * period, and we want a long delay occasionally to trigger
 340          * force_quiescent_state. */
 341
 342         if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
 343             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 344                 started = cur_ops->get_gp_seq();
 345                 ts = rcu_trace_clock_local();
 346                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 347                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 348                 mdelay(longdelay_ms);
 349                 rtrsp->rt_delay_ms = longdelay_ms;
 350                 completed = cur_ops->get_gp_seq();
 351                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 352                                           started, completed);
 353         }
 354         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 355                 udelay(shortdelay_us);
 356                 rtrsp->rt_delay_us = shortdelay_us;
 357         }
 358         if (!preempt_count() &&
 359             !(torture_random(rrsp) % (nrealreaders * 500))) {
 360                 torture_preempt_schedule();  /* QS only if preemptible. */
 361                 rtrsp->rt_preempted = true;
 362         }
 363 }
 364
 365 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 366 {
 367         rcu_read_unlock();
 368 }
 369
 370 /*
 371  * Update callback in the pipe.  This should be invoked after a grace period.
 372  */
 373 static bool
 374 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 375 {
 376         int i;
 377
 378         i = READ_ONCE(rp->rtort_pipe_count);
 379         if (i > RCU_TORTURE_PIPE_LEN)
 380                 i = RCU_TORTURE_PIPE_LEN;
 381         atomic_inc(&rcu_torture_wcount[i]);
 382         WRITE_ONCE(rp->rtort_pipe_count, i + 1);
 383         if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 384                 rp->rtort_mbtest = 0;
 385                 return true;
 386         }
 387         return false;
 388 }
 389
 390 /*
 391  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 392  * primitives.
 393  */
 394 static void
 395 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 396 {
 397         struct rcu_torture *rp;
 398         struct rcu_torture *rp1;
 399
 400         if (old_rp)
 401                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 402         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 403                 if (rcu_torture_pipe_update_one(rp)) {
 404                         list_del(&rp->rtort_free);
 405                         rcu_torture_free(rp);
 406                 }
 407         }
 408 }
 409
 410 static void
 411 rcu_torture_cb(struct rcu_head *p)
 412 {
 413         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 414
 415         if (torture_must_stop_irq()) {
 416                 /* Test is ending, just drop callbacks on the floor. */
 417                 /* The next initialization will pick up the pieces. */
 418                 return;
 419         }
 420         if (rcu_torture_pipe_update_one(rp))
 421                 rcu_torture_free(rp);
 422         else
 423                 cur_ops->deferred_free(rp);
 424 }
 425
 426 static unsigned long rcu_no_completed(void)
 427 {
 428         return 0;
 429 }
 430
 431 static void rcu_torture_deferred_free(struct rcu_torture *p)
 432 {
 433         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 434 }
 435
 436 static void rcu_sync_torture_init(void)
 437 {
 438         INIT_LIST_HEAD(&rcu_torture_removed);
 439 }
 440
 441 static struct rcu_torture_ops rcu_ops = {
 442         .ttype          = RCU_FLAVOR,
 443         .init           = rcu_sync_torture_init,
 444         .readlock       = rcu_torture_read_lock,
 445         .read_delay     = rcu_read_delay,
 446         .readunlock     = rcu_torture_read_unlock,
 447         .get_gp_seq     = rcu_get_gp_seq,
 448         .gp_diff        = rcu_seq_diff,
 449         .deferred_free  = rcu_torture_deferred_free,
 450         .sync           = synchronize_rcu,
 451         .exp_sync       = synchronize_rcu_expedited,
 452         .get_state      = get_state_synchronize_rcu,
 453         .cond_sync      = cond_synchronize_rcu,
 454         .call           = call_rcu,
 455         .cb_barrier     = rcu_barrier,
 456         .fqs            = rcu_force_quiescent_state,
 457         .stats          = NULL,
 458         .stall_dur      = rcu_jiffies_till_stall_check,
 459         .irq_capable    = 1,
 460         .can_boost      = rcu_can_boost(),
 461         .extendables    = RCUTORTURE_MAX_EXTEND,
 462         .name           = "rcu"
 463 };
 464
 465 /*
 466  * Don't even think about trying any of these in real life!!!
 467  * The names includes "busted", and they really means it!
 468  * The only purpose of these functions is to provide a buggy RCU
 469  * implementation to make sure that rcutorture correctly emits
 470  * buggy-RCU error messages.
 471  */
 472 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 473 {
 474         /* This is a deliberate bug for testing purposes only! */
 475         rcu_torture_cb(&p->rtort_rcu);
 476 }
 477
 478 static void synchronize_rcu_busted(void)
 479 {
 480         /* This is a deliberate bug for testing purposes only! */
 481 }
 482
 483 static void
 484 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 485 {
 486         /* This is a deliberate bug for testing purposes only! */
 487         func(head);
 488 }
 489
 490 static struct rcu_torture_ops rcu_busted_ops = {
 491         .ttype          = INVALID_RCU_FLAVOR,
 492         .init           = rcu_sync_torture_init,
 493         .readlock       = rcu_torture_read_lock,
 494         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 495         .readunlock     = rcu_torture_read_unlock,
 496         .get_gp_seq     = rcu_no_completed,
 497         .deferred_free  = rcu_busted_torture_deferred_free,
 498         .sync           = synchronize_rcu_busted,
 499         .exp_sync       = synchronize_rcu_busted,
 500         .call           = call_rcu_busted,
 501         .cb_barrier     = NULL,
 502         .fqs            = NULL,
 503         .stats          = NULL,
 504         .irq_capable    = 1,
 505         .name           = "busted"
 506 };
 507
 508 /*
 509  * Definitions for srcu torture testing.
 510  */
 511
 512 DEFINE_STATIC_SRCU(srcu_ctl);
 513 static struct srcu_struct srcu_ctld;
 514 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 515
 516 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 517 {
 518         return srcu_read_lock(srcu_ctlp);
 519 }
 520
 521 static void
 522 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 523 {
 524         long delay;
 525         const long uspertick = 1000000 / HZ;
 526         const long longdelay = 10;
 527
 528         /* We want there to be long-running readers, but not all the time. */
 529
 530         delay = torture_random(rrsp) %
 531                 (nrealreaders * 2 * longdelay * uspertick);
 532         if (!delay && in_task()) {
 533                 schedule_timeout_interruptible(longdelay);
 534                 rtrsp->rt_delay_jiffies = longdelay;
 535         } else {
 536                 rcu_read_delay(rrsp, rtrsp);
 537         }
 538 }
 539
 540 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 541 {
 542         srcu_read_unlock(srcu_ctlp, idx);
 543 }
 544
 545 static unsigned long srcu_torture_completed(void)
 546 {
 547         return srcu_batches_completed(srcu_ctlp);
 548 }
 549
 550 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 551 {
 552         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 553 }
 554
 555 static void srcu_torture_synchronize(void)
 556 {
 557         synchronize_srcu(srcu_ctlp);
 558 }
 559
 560 static void srcu_torture_call(struct rcu_head *head,
 561                               rcu_callback_t func)
 562 {
 563         call_srcu(srcu_ctlp, head, func);
 564 }
 565
 566 static void srcu_torture_barrier(void)
 567 {
 568         srcu_barrier(srcu_ctlp);
 569 }
 570
 571 static void srcu_torture_stats(void)
 572 {
 573         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 574 }
 575
 576 static void srcu_torture_synchronize_expedited(void)
 577 {
 578         synchronize_srcu_expedited(srcu_ctlp);
 579 }
 580
 581 static struct rcu_torture_ops srcu_ops = {
 582         .ttype          = SRCU_FLAVOR,
 583         .init           = rcu_sync_torture_init,
 584         .readlock       = srcu_torture_read_lock,
 585         .read_delay     = srcu_read_delay,
 586         .readunlock     = srcu_torture_read_unlock,
 587         .get_gp_seq     = srcu_torture_completed,
 588         .deferred_free  = srcu_torture_deferred_free,
 589         .sync           = srcu_torture_synchronize,
 590         .exp_sync       = srcu_torture_synchronize_expedited,
 591         .call           = srcu_torture_call,
 592         .cb_barrier     = srcu_torture_barrier,
 593         .stats          = srcu_torture_stats,
 594         .irq_capable    = 1,
 595         .name           = "srcu"
 596 };
 597
 598 static void srcu_torture_init(void)
 599 {
 600         rcu_sync_torture_init();
 601         WARN_ON(init_srcu_struct(&srcu_ctld));
 602         srcu_ctlp = &srcu_ctld;
 603 }
 604
 605 static void srcu_torture_cleanup(void)
 606 {
 607         cleanup_srcu_struct(&srcu_ctld);
 608         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 609 }
 610
 611 /* As above, but dynamically allocated. */
 612 static struct rcu_torture_ops srcud_ops = {
 613         .ttype          = SRCU_FLAVOR,
 614         .init           = srcu_torture_init,
 615         .cleanup        = srcu_torture_cleanup,
 616         .readlock       = srcu_torture_read_lock,
 617         .read_delay     = srcu_read_delay,
 618         .readunlock     = srcu_torture_read_unlock,
 619         .get_gp_seq     = srcu_torture_completed,
 620         .deferred_free  = srcu_torture_deferred_free,
 621         .sync           = srcu_torture_synchronize,
 622         .exp_sync       = srcu_torture_synchronize_expedited,
 623         .call           = srcu_torture_call,
 624         .cb_barrier     = srcu_torture_barrier,
 625         .stats          = srcu_torture_stats,
 626         .irq_capable    = 1,
 627         .name           = "srcud"
 628 };
 629
 630 /* As above, but broken due to inappropriate reader extension. */
 631 static struct rcu_torture_ops busted_srcud_ops = {
 632         .ttype          = SRCU_FLAVOR,
 633         .init           = srcu_torture_init,
 634         .cleanup        = srcu_torture_cleanup,
 635         .readlock       = srcu_torture_read_lock,
 636         .read_delay     = rcu_read_delay,
 637         .readunlock     = srcu_torture_read_unlock,
 638         .get_gp_seq     = srcu_torture_completed,
 639         .deferred_free  = srcu_torture_deferred_free,
 640         .sync           = srcu_torture_synchronize,
 641         .exp_sync       = srcu_torture_synchronize_expedited,
 642         .call           = srcu_torture_call,
 643         .cb_barrier     = srcu_torture_barrier,
 644         .stats          = srcu_torture_stats,
 645         .irq_capable    = 1,
 646         .extendables    = RCUTORTURE_MAX_EXTEND,
 647         .name           = "busted_srcud"
 648 };
 649
 650 /*
 651  * Definitions for RCU-tasks torture testing.
 652  */
 653
 654 static int tasks_torture_read_lock(void)
 655 {
 656         return 0;
 657 }
 658
 659 static void tasks_torture_read_unlock(int idx)
 660 {
 661 }
 662
 663 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 664 {
 665         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 666 }
 667
 668 static struct rcu_torture_ops tasks_ops = {
 669         .ttype          = RCU_TASKS_FLAVOR,
 670         .init           = rcu_sync_torture_init,
 671         .readlock       = tasks_torture_read_lock,
 672         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 673         .readunlock     = tasks_torture_read_unlock,
 674         .get_gp_seq     = rcu_no_completed,
 675         .deferred_free  = rcu_tasks_torture_deferred_free,
 676         .sync           = synchronize_rcu_tasks,
 677         .exp_sync       = synchronize_rcu_tasks,
 678         .call           = call_rcu_tasks,
 679         .cb_barrier     = rcu_barrier_tasks,
 680         .fqs            = NULL,
 681         .stats          = NULL,
 682         .irq_capable    = 1,
 683         .slow_gps       = 1,
 684         .name           = "tasks"
 685 };
 686
 687 /*
 688  * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 689  * This implementation does not necessarily work well with CPU hotplug.
 690  */
 691
 692 static void synchronize_rcu_trivial(void)
 693 {
 694         int cpu;
 695
 696         for_each_online_cpu(cpu) {
 697                 rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 698                 WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 699         }
 700 }
 701
 702 static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 703 {
 704         preempt_disable();
 705         return 0;
 706 }
 707
 708 static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 709 {
 710         preempt_enable();
 711 }
 712
 713 static struct rcu_torture_ops trivial_ops = {
 714         .ttype          = RCU_TRIVIAL_FLAVOR,
 715         .init           = rcu_sync_torture_init,
 716         .readlock       = rcu_torture_read_lock_trivial,
 717         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 718         .readunlock     = rcu_torture_read_unlock_trivial,
 719         .get_gp_seq     = rcu_no_completed,
 720         .sync           = synchronize_rcu_trivial,
 721         .exp_sync       = synchronize_rcu_trivial,
 722         .fqs            = NULL,
 723         .stats          = NULL,
 724         .irq_capable    = 1,
 725         .name           = "trivial"
 726 };
 727
 728 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 729 {
 730         if (!cur_ops->gp_diff)
 731                 return new - old;
 732         return cur_ops->gp_diff(new, old);
 733 }
 734
 735 static bool __maybe_unused torturing_tasks(void)
 736 {
 737         return cur_ops == &tasks_ops;
 738 }
 739
 740 /*
 741  * RCU torture priority-boost testing.  Runs one real-time thread per
 742  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 743  * spinning waiting for them to be invoked.  If a given callback takes
 744  * too long to be invoked, we assume that priority inversion has occurred.
 745  */
 746
 747 struct rcu_boost_inflight {
 748         struct rcu_head rcu;
 749         int inflight;
 750 };
 751
 752 static void rcu_torture_boost_cb(struct rcu_head *head)
 753 {
 754         struct rcu_boost_inflight *rbip =
 755                 container_of(head, struct rcu_boost_inflight, rcu);
 756
 757         /* Ensure RCU-core accesses precede clearing ->inflight */
 758         smp_store_release(&rbip->inflight, 0);
 759 }
 760
 761 static int old_rt_runtime = -1;
 762
 763 static void rcu_torture_disable_rt_throttle(void)
 764 {
 765         /*
 766          * Disable RT throttling so that rcutorture's boost threads don't get
 767          * throttled. Only possible if rcutorture is built-in otherwise the
 768          * user should manually do this by setting the sched_rt_period_us and
 769          * sched_rt_runtime sysctls.
 770          */
 771         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 772                 return;
 773
 774         old_rt_runtime = sysctl_sched_rt_runtime;
 775         sysctl_sched_rt_runtime = -1;
 776 }
 777
 778 static void rcu_torture_enable_rt_throttle(void)
 779 {
 780         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 781                 return;
 782
 783         sysctl_sched_rt_runtime = old_rt_runtime;
 784         old_rt_runtime = -1;
 785 }
 786
 787 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 788 {
 789         if (end - start > test_boost_duration * HZ - HZ / 2) {
 790                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 791                 n_rcu_torture_boost_failure++;
 792
 793                 return true; /* failed */
 794         }
 795
 796         return false; /* passed */
 797 }
 798
 799 static int rcu_torture_boost(void *arg)
 800 {
 801         unsigned long call_rcu_time;
 802         unsigned long endtime;
 803         unsigned long oldstarttime;
 804         struct rcu_boost_inflight rbi = { .inflight = 0 };
 805         struct sched_param sp;
 806
 807         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 808
 809         /* Set real-time priority. */
 810         sp.sched_priority = 1;
 811         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 812                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 813                 n_rcu_torture_boost_rterror++;
 814         }
 815
 816         init_rcu_head_on_stack(&rbi.rcu);
 817         /* Each pass through the following loop does one boost-test cycle. */
 818         do {
 819                 /* Track if the test failed already in this test interval? */
 820                 bool failed = false;
 821
 822                 /* Increment n_rcu_torture_boosts once per boost-test */
 823                 while (!kthread_should_stop()) {
 824                         if (mutex_trylock(&boost_mutex)) {
 825                                 n_rcu_torture_boosts++;
 826                                 mutex_unlock(&boost_mutex);
 827                                 break;
 828                         }
 829                         schedule_timeout_uninterruptible(1);
 830                 }
 831                 if (kthread_should_stop())
 832                         goto checkwait;
 833
 834                 /* Wait for the next test interval. */
 835                 oldstarttime = boost_starttime;
 836                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 837                         schedule_timeout_interruptible(oldstarttime - jiffies);
 838                         stutter_wait("rcu_torture_boost");
 839                         if (torture_must_stop())
 840                                 goto checkwait;
 841                 }
 842
 843                 /* Do one boost-test interval. */
 844                 endtime = oldstarttime + test_boost_duration * HZ;
 845                 call_rcu_time = jiffies;
 846                 while (ULONG_CMP_LT(jiffies, endtime)) {
 847                         /* If we don't have a callback in flight, post one. */
 848                         if (!smp_load_acquire(&rbi.inflight)) {
 849                                 /* RCU core before ->inflight = 1. */
 850                                 smp_store_release(&rbi.inflight, 1);
 851                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 852                                 /* Check if the boost test failed */
 853                                 failed = failed ||
 854                                          rcu_torture_boost_failed(call_rcu_time,
 855                                                                  jiffies);
 856                                 call_rcu_time = jiffies;
 857                         }
 858                         stutter_wait("rcu_torture_boost");
 859                         if (torture_must_stop())
 860                                 goto checkwait;
 861                 }
 862
 863                 /*
 864                  * If boost never happened, then inflight will always be 1, in
 865                  * this case the boost check would never happen in the above
 866                  * loop so do another one here.
 867                  */
 868                 if (!failed && smp_load_acquire(&rbi.inflight))
 869                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 870
 871                 /*
 872                  * Set the start time of the next test interval.
 873                  * Yes, this is vulnerable to long delays, but such
 874                  * delays simply cause a false negative for the next
 875                  * interval.  Besides, we are running at RT priority,
 876                  * so delays should be relatively rare.
 877                  */
 878                 while (oldstarttime == boost_starttime &&
 879                        !kthread_should_stop()) {
 880                         if (mutex_trylock(&boost_mutex)) {
 881                                 boost_starttime = jiffies +
 882                                                   test_boost_interval * HZ;
 883                                 mutex_unlock(&boost_mutex);
 884                                 break;
 885                         }
 886                         schedule_timeout_uninterruptible(1);
 887                 }
 888
 889                 /* Go do the stutter. */
 890 checkwait:      stutter_wait("rcu_torture_boost");
 891         } while (!torture_must_stop());
 892
 893         /* Clean up and exit. */
 894         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 895                 torture_shutdown_absorb("rcu_torture_boost");
 896                 schedule_timeout_uninterruptible(1);
 897         }
 898         destroy_rcu_head_on_stack(&rbi.rcu);
 899         torture_kthread_stopping("rcu_torture_boost");
 900         return 0;
 901 }
 902
 903 /*
 904  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 905  * bursts of calls to force_quiescent_state(), increasing the probability
 906  * of occurrence of some important types of race conditions.
 907  */
 908 static int
 909 rcu_torture_fqs(void *arg)
 910 {
 911         unsigned long fqs_resume_time;
 912         int fqs_burst_remaining;
 913
 914         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 915         do {
 916                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 917                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 918                        !kthread_should_stop()) {
 919                         schedule_timeout_interruptible(1);
 920                 }
 921                 fqs_burst_remaining = fqs_duration;
 922                 while (fqs_burst_remaining > 0 &&
 923                        !kthread_should_stop()) {
 924                         cur_ops->fqs();
 925                         udelay(fqs_holdoff);
 926                         fqs_burst_remaining -= fqs_holdoff;
 927                 }
 928                 stutter_wait("rcu_torture_fqs");
 929         } while (!torture_must_stop());
 930         torture_kthread_stopping("rcu_torture_fqs");
 931         return 0;
 932 }
 933
 934 /*
 935  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 936  * for that pointed to by rcu_torture_current, freeing the old structure
 937  * after a series of grace periods (the "pipeline").
 938  */
 939 static int
 940 rcu_torture_writer(void *arg)
 941 {
 942         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 943         int expediting = 0;
 944         unsigned long gp_snap;
 945         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 946         bool gp_sync1 = gp_sync;
 947         int i;
 948         struct rcu_torture *rp;
 949         struct rcu_torture *old_rp;
 950         static DEFINE_TORTURE_RANDOM(rand);
 951         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 952                            RTWS_COND_GET, RTWS_SYNC };
 953         int nsynctypes = 0;
 954
 955         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 956         if (!can_expedite)
 957                 pr_alert("%s" TORTURE_FLAG
 958                          " GP expediting controlled from boot/sysfs for %s.\n",
 959                          torture_type, cur_ops->name);
 960
 961         /* Initialize synctype[] array.  If none set, take default. */
 962         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 963                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 964         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 965                 synctype[nsynctypes++] = RTWS_COND_GET;
 966                 pr_info("%s: Testing conditional GPs.\n", __func__);
 967         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 968                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 969         }
 970         if (gp_exp1 && cur_ops->exp_sync) {
 971                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 972                 pr_info("%s: Testing expedited GPs.\n", __func__);
 973         } else if (gp_exp && !cur_ops->exp_sync) {
 974                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 975         }
 976         if (gp_normal1 && cur_ops->deferred_free) {
 977                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 978                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 979         } else if (gp_normal && !cur_ops->deferred_free) {
 980                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 981         }
 982         if (gp_sync1 && cur_ops->sync) {
 983                 synctype[nsynctypes++] = RTWS_SYNC;
 984                 pr_info("%s: Testing normal GPs.\n", __func__);
 985         } else if (gp_sync && !cur_ops->sync) {
 986                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 987         }
 988         if (WARN_ONCE(nsynctypes == 0,
 989                       "rcu_torture_writer: No update-side primitives.\n")) {
 990                 /*
 991                  * No updates primitives, so don't try updating.
 992                  * The resulting test won't be testing much, hence the
 993                  * above WARN_ONCE().
 994                  */
 995                 rcu_torture_writer_state = RTWS_STOPPING;
 996                 torture_kthread_stopping("rcu_torture_writer");
 997         }
 998
 999         do {
1000                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
1001                 schedule_timeout_uninterruptible(1);
1002                 rp = rcu_torture_alloc();
1003                 if (rp == NULL)
1004                         continue;
1005                 rp->rtort_pipe_count = 0;
1006                 rcu_torture_writer_state = RTWS_DELAY;
1007                 udelay(torture_random(&rand) & 0x3ff);
1008                 rcu_torture_writer_state = RTWS_REPLACE;
1009                 old_rp = rcu_dereference_check(rcu_torture_current,
1010                                                current == writer_task);
1011                 rp->rtort_mbtest = 1;
1012                 rcu_assign_pointer(rcu_torture_current, rp);
1013                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1014                 if (old_rp) {
1015                         i = old_rp->rtort_pipe_count;
1016                         if (i > RCU_TORTURE_PIPE_LEN)
1017                                 i = RCU_TORTURE_PIPE_LEN;
1018                         atomic_inc(&rcu_torture_wcount[i]);
1019                         WRITE_ONCE(old_rp->rtort_pipe_count,
1020                                    old_rp->rtort_pipe_count + 1);
1021                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1022                         case RTWS_DEF_FREE:
1023                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1024                                 cur_ops->deferred_free(old_rp);
1025                                 break;
1026                         case RTWS_EXP_SYNC:
1027                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1028                                 cur_ops->exp_sync();
1029                                 rcu_torture_pipe_update(old_rp);
1030                                 break;
1031                         case RTWS_COND_GET:
1032                                 rcu_torture_writer_state = RTWS_COND_GET;
1033                                 gp_snap = cur_ops->get_state();
1034                                 i = torture_random(&rand) % 16;
1035                                 if (i != 0)
1036                                         schedule_timeout_interruptible(i);
1037                                 udelay(torture_random(&rand) % 1000);
1038                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1039                                 cur_ops->cond_sync(gp_snap);
1040                                 rcu_torture_pipe_update(old_rp);
1041                                 break;
1042                         case RTWS_SYNC:
1043                                 rcu_torture_writer_state = RTWS_SYNC;
1044                                 cur_ops->sync();
1045                                 rcu_torture_pipe_update(old_rp);
1046                                 break;
1047                         default:
1048                                 WARN_ON_ONCE(1);
1049                                 break;
1050                         }
1051                 }
1052                 WRITE_ONCE(rcu_torture_current_version,
1053                            rcu_torture_current_version + 1);
1054                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1055                 if (can_expedite &&
1056                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1057                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1058                         if (expediting >= 0)
1059                                 rcu_expedite_gp();
1060                         else
1061                                 rcu_unexpedite_gp();
1062                         if (++expediting > 3)
1063                                 expediting = -expediting;
1064                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1065                         can_expedite = !rcu_gp_is_expedited() &&
1066                                        !rcu_gp_is_normal();
1067                 }
1068                 rcu_torture_writer_state = RTWS_STUTTER;
1069                 if (stutter_wait("rcu_torture_writer") &&
1070                     !READ_ONCE(rcu_fwd_cb_nodelay) &&
1071                     !cur_ops->slow_gps &&
1072                     !torture_must_stop() &&
1073                     rcu_inkernel_boot_has_ended())
1074                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1075                                 if (list_empty(&rcu_tortures[i].rtort_free) &&
1076                                     rcu_access_pointer(rcu_torture_current) !=
1077                                     &rcu_tortures[i]) {
1078                                         rcu_ftrace_dump(DUMP_ALL);
1079                                         WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1080                                 }
1081         } while (!torture_must_stop());
1082         /* Reset expediting back to unexpedited. */
1083         if (expediting > 0)
1084                 expediting = -expediting;
1085         while (can_expedite && expediting++ < 0)
1086                 rcu_unexpedite_gp();
1087         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1088         if (!can_expedite)
1089                 pr_alert("%s" TORTURE_FLAG
1090                          " Dynamic grace-period expediting was disabled.\n",
1091                          torture_type);
1092         rcu_torture_writer_state = RTWS_STOPPING;
1093         torture_kthread_stopping("rcu_torture_writer");
1094         return 0;
1095 }
1096
1097 /*
1098  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1099  * delay between calls.
1100  */
1101 static int
1102 rcu_torture_fakewriter(void *arg)
1103 {
1104         DEFINE_TORTURE_RANDOM(rand);
1105
1106         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1107         set_user_nice(current, MAX_NICE);
1108
1109         do {
1110                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1111                 udelay(torture_random(&rand) & 0x3ff);
1112                 if (cur_ops->cb_barrier != NULL &&
1113                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1114                         cur_ops->cb_barrier();
1115                 } else if (gp_normal == gp_exp) {
1116                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1117                                 cur_ops->sync();
1118                         else if (cur_ops->exp_sync)
1119                                 cur_ops->exp_sync();
1120                 } else if (gp_normal && cur_ops->sync) {
1121                         cur_ops->sync();
1122                 } else if (cur_ops->exp_sync) {
1123                         cur_ops->exp_sync();
1124                 }
1125                 stutter_wait("rcu_torture_fakewriter");
1126         } while (!torture_must_stop());
1127
1128         torture_kthread_stopping("rcu_torture_fakewriter");
1129         return 0;
1130 }
1131
1132 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1133 {
1134         kfree(rhp);
1135 }
1136
1137 /*
1138  * Do one extension of an RCU read-side critical section using the
1139  * current reader state in readstate (set to zero for initial entry
1140  * to extended critical section), set the new state as specified by
1141  * newstate (set to zero for final exit from extended critical section),
1142  * and random-number-generator state in trsp.  If this is neither the
1143  * beginning or end of the critical section and if there was actually a
1144  * change, do a ->read_delay().
1145  */
1146 static void rcutorture_one_extend(int *readstate, int newstate,
1147                                   struct torture_random_state *trsp,
1148                                   struct rt_read_seg *rtrsp)
1149 {
1150         int idxnew = -1;
1151         int idxold = *readstate;
1152         int statesnew = ~*readstate & newstate;
1153         int statesold = *readstate & ~newstate;
1154
1155         WARN_ON_ONCE(idxold < 0);
1156         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1157         rtrsp->rt_readstate = newstate;
1158
1159         /* First, put new protection in place to avoid critical-section gap. */
1160         if (statesnew & RCUTORTURE_RDR_BH)
1161                 local_bh_disable();
1162         if (statesnew & RCUTORTURE_RDR_IRQ)
1163                 local_irq_disable();
1164         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1165                 preempt_disable();
1166         if (statesnew & RCUTORTURE_RDR_RBH)
1167                 rcu_read_lock_bh();
1168         if (statesnew & RCUTORTURE_RDR_SCHED)
1169                 rcu_read_lock_sched();
1170         if (statesnew & RCUTORTURE_RDR_RCU)
1171                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1172
1173         /* Next, remove old protection, irq first due to bh conflict. */
1174         if (statesold & RCUTORTURE_RDR_IRQ)
1175                 local_irq_enable();
1176         if (statesold & RCUTORTURE_RDR_BH)
1177                 local_bh_enable();
1178         if (statesold & RCUTORTURE_RDR_PREEMPT)
1179                 preempt_enable();
1180         if (statesold & RCUTORTURE_RDR_RBH)
1181                 rcu_read_unlock_bh();
1182         if (statesold & RCUTORTURE_RDR_SCHED)
1183                 rcu_read_unlock_sched();
1184         if (statesold & RCUTORTURE_RDR_RCU)
1185                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1186
1187         /* Delay if neither beginning nor end and there was a change. */
1188         if ((statesnew || statesold) && *readstate && newstate)
1189                 cur_ops->read_delay(trsp, rtrsp);
1190
1191         /* Update the reader state. */
1192         if (idxnew == -1)
1193                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1194         WARN_ON_ONCE(idxnew < 0);
1195         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1196         *readstate = idxnew | newstate;
1197         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1198         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1199 }
1200
1201 /* Return the biggest extendables mask given current RCU and boot parameters. */
1202 static int rcutorture_extend_mask_max(void)
1203 {
1204         int mask;
1205
1206         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1207         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1208         mask = mask | RCUTORTURE_RDR_RCU;
1209         return mask;
1210 }
1211
1212 /* Return a random protection state mask, but with at least one bit set. */
1213 static int
1214 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1215 {
1216         int mask = rcutorture_extend_mask_max();
1217         unsigned long randmask1 = torture_random(trsp) >> 8;
1218         unsigned long randmask2 = randmask1 >> 3;
1219
1220         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1221         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1222         if (!(randmask1 & 0x7))
1223                 mask = mask & randmask2;
1224         else
1225                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1226         /* Can't enable bh w/irq disabled. */
1227         if ((mask & RCUTORTURE_RDR_IRQ) &&
1228             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1229              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1230                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1231         return mask ?: RCUTORTURE_RDR_RCU;
1232 }
1233
1234 /*
1235  * Do a randomly selected number of extensions of an existing RCU read-side
1236  * critical section.
1237  */
1238 static struct rt_read_seg *
1239 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1240                        struct rt_read_seg *rtrsp)
1241 {
1242         int i;
1243         int j;
1244         int mask = rcutorture_extend_mask_max();
1245
1246         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1247         if (!((mask - 1) & mask))
1248                 return rtrsp;  /* Current RCU reader not extendable. */
1249         /* Bias towards larger numbers of loops. */
1250         i = (torture_random(trsp) >> 3);
1251         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1252         for (j = 0; j < i; j++) {
1253                 mask = rcutorture_extend_mask(*readstate, trsp);
1254                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1255         }
1256         return &rtrsp[j];
1257 }
1258
1259 /*
1260  * Do one read-side critical section, returning false if there was
1261  * no data to read.  Can be invoked both from process context and
1262  * from a timer handler.
1263  */
1264 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1265 {
1266         int i;
1267         unsigned long started;
1268         unsigned long completed;
1269         int newstate;
1270         struct rcu_torture *p;
1271         int pipe_count;
1272         int readstate = 0;
1273         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1274         struct rt_read_seg *rtrsp = &rtseg[0];
1275         struct rt_read_seg *rtrsp1;
1276         unsigned long long ts;
1277
1278         newstate = rcutorture_extend_mask(readstate, trsp);
1279         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1280         started = cur_ops->get_gp_seq();
1281         ts = rcu_trace_clock_local();
1282         p = rcu_dereference_check(rcu_torture_current,
1283                                   rcu_read_lock_bh_held() ||
1284                                   rcu_read_lock_sched_held() ||
1285                                   srcu_read_lock_held(srcu_ctlp) ||
1286                                   torturing_tasks());
1287         if (p == NULL) {
1288                 /* Wait for rcu_torture_writer to get underway */
1289                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1290                 return false;
1291         }
1292         if (p->rtort_mbtest == 0)
1293                 atomic_inc(&n_rcu_torture_mberror);
1294         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1295         preempt_disable();
1296         pipe_count = READ_ONCE(p->rtort_pipe_count);
1297         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1298                 /* Should not happen, but... */
1299                 pipe_count = RCU_TORTURE_PIPE_LEN;
1300         }
1301         completed = cur_ops->get_gp_seq();
1302         if (pipe_count > 1) {
1303                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1304                                           ts, started, completed);
1305                 rcu_ftrace_dump(DUMP_ALL);
1306         }
1307         __this_cpu_inc(rcu_torture_count[pipe_count]);
1308         completed = rcutorture_seq_diff(completed, started);
1309         if (completed > RCU_TORTURE_PIPE_LEN) {
1310                 /* Should not happen, but... */
1311                 completed = RCU_TORTURE_PIPE_LEN;
1312         }
1313         __this_cpu_inc(rcu_torture_batch[completed]);
1314         preempt_enable();
1315         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1316         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1317
1318         /* If error or close call, record the sequence of reader protections. */
1319         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1320                 i = 0;
1321                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1322                         err_segs[i++] = *rtrsp1;
1323                 rt_read_nsegs = i;
1324         }
1325
1326         return true;
1327 }
1328
1329 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1330
1331 /*
1332  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1333  * incrementing the corresponding element of the pipeline array.  The
1334  * counter in the element should never be greater than 1, otherwise, the
1335  * RCU implementation is broken.
1336  */
1337 static void rcu_torture_timer(struct timer_list *unused)
1338 {
1339         atomic_long_inc(&n_rcu_torture_timers);
1340         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1341
1342         /* Test call_rcu() invocation from interrupt handler. */
1343         if (cur_ops->call) {
1344                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1345
1346                 if (rhp)
1347                         cur_ops->call(rhp, rcu_torture_timer_cb);
1348         }
1349 }
1350
1351 /*
1352  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1353  * incrementing the corresponding element of the pipeline array.  The
1354  * counter in the element should never be greater than 1, otherwise, the
1355  * RCU implementation is broken.
1356  */
1357 static int
1358 rcu_torture_reader(void *arg)
1359 {
1360         unsigned long lastsleep = jiffies;
1361         long myid = (long)arg;
1362         int mynumonline = myid;
1363         DEFINE_TORTURE_RANDOM(rand);
1364         struct timer_list t;
1365
1366         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1367         set_user_nice(current, MAX_NICE);
1368         if (irqreader && cur_ops->irq_capable)
1369                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1370         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
1371         do {
1372                 if (irqreader && cur_ops->irq_capable) {
1373                         if (!timer_pending(&t))
1374                                 mod_timer(&t, jiffies + 1);
1375                 }
1376                 if (!rcu_torture_one_read(&rand) && !torture_must_stop())
1377                         schedule_timeout_interruptible(HZ);
1378                 if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
1379                         schedule_timeout_interruptible(1);
1380                         lastsleep = jiffies + 10;
1381                 }
1382                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1383                         schedule_timeout_interruptible(HZ / 5);
1384                 stutter_wait("rcu_torture_reader");
1385         } while (!torture_must_stop());
1386         if (irqreader && cur_ops->irq_capable) {
1387                 del_timer_sync(&t);
1388                 destroy_timer_on_stack(&t);
1389         }
1390         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
1391         torture_kthread_stopping("rcu_torture_reader");
1392         return 0;
1393 }
1394
1395 /*
1396  * Print torture statistics.  Caller must ensure that there is only
1397  * one call to this function at a given time!!!  This is normally
1398  * accomplished by relying on the module system to only have one copy
1399  * of the module loaded, and then by giving the rcu_torture_stats
1400  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1401  * thread is not running).
1402  */
1403 static void
1404 rcu_torture_stats_print(void)
1405 {
1406         int cpu;
1407         int i;
1408         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1409         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1410         struct rcu_torture *rtcp;
1411         static unsigned long rtcv_snap = ULONG_MAX;
1412         static bool splatted;
1413         struct task_struct *wtp;
1414
1415         for_each_possible_cpu(cpu) {
1416                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1417                         pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
1418                         batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
1419                 }
1420         }
1421         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1422                 if (pipesummary[i] != 0)
1423                         break;
1424         }
1425
1426         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1427         rtcp = rcu_access_pointer(rcu_torture_current);
1428         pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1429                 rtcp,
1430                 rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
1431                 rcu_torture_current_version,
1432                 list_empty(&rcu_torture_freelist),
1433                 atomic_read(&n_rcu_torture_alloc),
1434                 atomic_read(&n_rcu_torture_alloc_fail),
1435                 atomic_read(&n_rcu_torture_free));
1436         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1437                 atomic_read(&n_rcu_torture_mberror),
1438                 n_rcu_torture_barrier_error,
1439                 n_rcu_torture_boost_ktrerror,
1440                 n_rcu_torture_boost_rterror);
1441         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1442                 n_rcu_torture_boost_failure,
1443                 n_rcu_torture_boosts,
1444                 atomic_long_read(&n_rcu_torture_timers));
1445         torture_onoff_stats();
1446         pr_cont("barrier: %ld/%ld:%ld\n",
1447                 n_barrier_successes,
1448                 n_barrier_attempts,
1449                 n_rcu_torture_barrier_error);
1450
1451         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1452         if (atomic_read(&n_rcu_torture_mberror) ||
1453             n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
1454             n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
1455             i > 1) {
1456                 pr_cont("%s", "!!! ");
1457                 atomic_inc(&n_rcu_torture_error);
1458                 WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
1459                 WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
1460                 WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
1461                 WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
1462                 WARN_ON_ONCE(n_rcu_torture_boost_failure); // RCU boost failed
1463                 WARN_ON_ONCE(i > 1); // Too-short grace period
1464         }
1465         pr_cont("Reader Pipe: ");
1466         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1467                 pr_cont(" %ld", pipesummary[i]);
1468         pr_cont("\n");
1469
1470         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1471         pr_cont("Reader Batch: ");
1472         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1473                 pr_cont(" %ld", batchsummary[i]);
1474         pr_cont("\n");
1475
1476         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1477         pr_cont("Free-Block Circulation: ");
1478         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1479                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1480         }
1481         pr_cont("\n");
1482
1483         if (cur_ops->stats)
1484                 cur_ops->stats();
1485         if (rtcv_snap == rcu_torture_current_version &&
1486             rcu_access_pointer(rcu_torture_current) &&
1487             !rcu_stall_is_suppressed()) {
1488                 int __maybe_unused flags = 0;
1489                 unsigned long __maybe_unused gp_seq = 0;
1490
1491                 rcutorture_get_gp_data(cur_ops->ttype,
1492                                        &flags, &gp_seq);
1493                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1494                                         &flags, &gp_seq);
1495                 wtp = READ_ONCE(writer_task);
1496                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1497                          rcu_torture_writer_state_getname(),
1498                          rcu_torture_writer_state, gp_seq, flags,
1499                          wtp == NULL ? ~0UL : wtp->state,
1500                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1501                 if (!splatted && wtp) {
1502                         sched_show_task(wtp);
1503                         splatted = true;
1504                 }
1505                 show_rcu_gp_kthreads();
1506                 rcu_ftrace_dump(DUMP_ALL);
1507         }
1508         rtcv_snap = rcu_torture_current_version;
1509 }
1510
1511 /*
1512  * Periodically prints torture statistics, if periodic statistics printing
1513  * was specified via the stat_interval module parameter.
1514  */
1515 static int
1516 rcu_torture_stats(void *arg)
1517 {
1518         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1519         do {
1520                 schedule_timeout_interruptible(stat_interval * HZ);
1521                 rcu_torture_stats_print();
1522                 torture_shutdown_absorb("rcu_torture_stats");
1523         } while (!torture_must_stop());
1524         torture_kthread_stopping("rcu_torture_stats");
1525         return 0;
1526 }
1527
1528 static void
1529 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1530 {
1531         pr_alert("%s" TORTURE_FLAG
1532                  "--- %s: nreaders=%d nfakewriters=%d "
1533                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1534                  "shuffle_interval=%d stutter=%d irqreader=%d "
1535                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1536                  "test_boost=%d/%d test_boost_interval=%d "
1537                  "test_boost_duration=%d shutdown_secs=%d "
1538                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1539                  "n_barrier_cbs=%d "
1540                  "onoff_interval=%d onoff_holdoff=%d\n",
1541                  torture_type, tag, nrealreaders, nfakewriters,
1542                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1543                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1544                  test_boost, cur_ops->can_boost,
1545                  test_boost_interval, test_boost_duration, shutdown_secs,
1546                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1547                  n_barrier_cbs,
1548                  onoff_interval, onoff_holdoff);
1549 }
1550
1551 static int rcutorture_booster_cleanup(unsigned int cpu)
1552 {
1553         struct task_struct *t;
1554
1555         if (boost_tasks[cpu] == NULL)
1556                 return 0;
1557         mutex_lock(&boost_mutex);
1558         t = boost_tasks[cpu];
1559         boost_tasks[cpu] = NULL;
1560         rcu_torture_enable_rt_throttle();
1561         mutex_unlock(&boost_mutex);
1562
1563         /* This must be outside of the mutex, otherwise deadlock! */
1564         torture_stop_kthread(rcu_torture_boost, t);
1565         return 0;
1566 }
1567
1568 static int rcutorture_booster_init(unsigned int cpu)
1569 {
1570         int retval;
1571
1572         if (boost_tasks[cpu] != NULL)
1573                 return 0;  /* Already created, nothing more to do. */
1574
1575         /* Don't allow time recalculation while creating a new task. */
1576         mutex_lock(&boost_mutex);
1577         rcu_torture_disable_rt_throttle();
1578         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1579         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1580                                                   cpu_to_node(cpu),
1581                                                   "rcu_torture_boost");
1582         if (IS_ERR(boost_tasks[cpu])) {
1583                 retval = PTR_ERR(boost_tasks[cpu]);
1584                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1585                 n_rcu_torture_boost_ktrerror++;
1586                 boost_tasks[cpu] = NULL;
1587                 mutex_unlock(&boost_mutex);
1588                 return retval;
1589         }
1590         kthread_bind(boost_tasks[cpu], cpu);
1591         wake_up_process(boost_tasks[cpu]);
1592         mutex_unlock(&boost_mutex);
1593         return 0;
1594 }
1595
1596 /*
1597  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1598  * induces a CPU stall for the time specified by stall_cpu.
1599  */
1600 static int rcu_torture_stall(void *args)
1601 {
1602         unsigned long stop_at;
1603
1604         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1605         if (stall_cpu_holdoff > 0) {
1606                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1607                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1608                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1609         }
1610         if (!kthread_should_stop()) {
1611                 stop_at = ktime_get_seconds() + stall_cpu;
1612                 /* RCU CPU stall is expected behavior in following code. */
1613                 rcu_read_lock();
1614                 if (stall_cpu_irqsoff)
1615                         local_irq_disable();
1616                 else
1617                         preempt_disable();
1618                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1619                          smp_processor_id());
1620                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1621                                     stop_at))
1622                         continue;  /* Induce RCU CPU stall warning. */
1623                 if (stall_cpu_irqsoff)
1624                         local_irq_enable();
1625                 else
1626                         preempt_enable();
1627                 rcu_read_unlock();
1628                 pr_alert("rcu_torture_stall end.\n");
1629         }
1630         torture_shutdown_absorb("rcu_torture_stall");
1631         while (!kthread_should_stop())
1632                 schedule_timeout_interruptible(10 * HZ);
1633         return 0;
1634 }
1635
1636 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1637 static int __init rcu_torture_stall_init(void)
1638 {
1639         if (stall_cpu <= 0)
1640                 return 0;
1641         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1642 }
1643
1644 /* State structure for forward-progress self-propagating RCU callback. */
1645 struct fwd_cb_state {
1646         struct rcu_head rh;
1647         int stop;
1648 };
1649
1650 /*
1651  * Forward-progress self-propagating RCU callback function.  Because
1652  * callbacks run from softirq, this function is an implicit RCU read-side
1653  * critical section.
1654  */
1655 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1656 {
1657         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1658
1659         if (READ_ONCE(fcsp->stop)) {
1660                 WRITE_ONCE(fcsp->stop, 2);
1661                 return;
1662         }
1663         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1664 }
1665
1666 /* State for continuous-flood RCU callbacks. */
1667 struct rcu_fwd_cb {
1668         struct rcu_head rh;
1669         struct rcu_fwd_cb *rfc_next;
1670         struct rcu_fwd *rfc_rfp;
1671         int rfc_gps;
1672 };
1673
1674 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1675 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1676 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1677 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1678 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1679
1680 struct rcu_launder_hist {
1681         long n_launders;
1682         unsigned long launder_gp_seq;
1683 };
1684
1685 struct rcu_fwd {
1686         spinlock_t rcu_fwd_lock;
1687         struct rcu_fwd_cb *rcu_fwd_cb_head;
1688         struct rcu_fwd_cb **rcu_fwd_cb_tail;
1689         long n_launders_cb;
1690         unsigned long rcu_fwd_startat;
1691         struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1692         unsigned long rcu_launder_gp_seq_start;
1693 };
1694
1695 struct rcu_fwd *rcu_fwds;
1696 bool rcu_fwd_emergency_stop;
1697
1698 static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
1699 {
1700         unsigned long gps;
1701         unsigned long gps_old;
1702         int i;
1703         int j;
1704
1705         for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
1706                 if (rfp->n_launders_hist[i].n_launders > 0)
1707                         break;
1708         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1709                  __func__, jiffies - rfp->rcu_fwd_startat);
1710         gps_old = rfp->rcu_launder_gp_seq_start;
1711         for (j = 0; j <= i; j++) {
1712                 gps = rfp->n_launders_hist[j].launder_gp_seq;
1713                 pr_cont(" %ds/%d: %ld:%ld",
1714                         j + 1, FWD_CBS_HIST_DIV,
1715                         rfp->n_launders_hist[j].n_launders,
1716                         rcutorture_seq_diff(gps, gps_old));
1717                 gps_old = gps;
1718         }
1719         pr_cont("\n");
1720 }
1721
1722 /* Callback function for continuous-flood RCU callbacks. */
1723 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1724 {
1725         unsigned long flags;
1726         int i;
1727         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1728         struct rcu_fwd_cb **rfcpp;
1729         struct rcu_fwd *rfp = rfcp->rfc_rfp;
1730
1731         rfcp->rfc_next = NULL;
1732         rfcp->rfc_gps++;
1733         spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
1734         rfcpp = rfp->rcu_fwd_cb_tail;
1735         rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
1736         WRITE_ONCE(*rfcpp, rfcp);
1737         WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
1738         i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1739         if (i >= ARRAY_SIZE(rfp->n_launders_hist))
1740                 i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
1741         rfp->n_launders_hist[i].n_launders++;
1742         rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1743         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1744 }
1745
1746 // Give the scheduler a chance, even on nohz_full CPUs.
1747 static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
1748 {
1749         if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
1750                 // Real call_rcu() floods hit userspace, so emulate that.
1751                 if (need_resched() || (iter & 0xfff))
1752                         schedule();
1753                 return;
1754         }
1755         // No userspace emulation: CB invocation throttles call_rcu()
1756         cond_resched();
1757 }
1758
1759 /*
1760  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1761  * test is over or because we hit an OOM event.
1762  */
1763 static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
1764 {
1765         unsigned long flags;
1766         unsigned long freed = 0;
1767         struct rcu_fwd_cb *rfcp;
1768
1769         for (;;) {
1770                 spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
1771                 rfcp = rfp->rcu_fwd_cb_head;
1772                 if (!rfcp) {
1773                         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1774                         break;
1775                 }
1776                 rfp->rcu_fwd_cb_head = rfcp->rfc_next;
1777                 if (!rfp->rcu_fwd_cb_head)
1778                         rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
1779                 spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1780                 kfree(rfcp);
1781                 freed++;
1782                 rcu_torture_fwd_prog_cond_resched(freed);
1783                 if (tick_nohz_full_enabled()) {
1784                         local_irq_save(flags);
1785                         rcu_momentary_dyntick_idle();
1786                         local_irq_restore(flags);
1787                 }
1788         }
1789         return freed;
1790 }
1791
1792 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1793 static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
1794                                     int *tested, int *tested_tries)
1795 {
1796         unsigned long cver;
1797         unsigned long dur;
1798         struct fwd_cb_state fcs;
1799         unsigned long gps;
1800         int idx;
1801         int sd;
1802         int sd4;
1803         bool selfpropcb = false;
1804         unsigned long stopat;
1805         static DEFINE_TORTURE_RANDOM(trs);
1806
1807         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1808                 init_rcu_head_on_stack(&fcs.rh);
1809                 selfpropcb = true;
1810         }
1811
1812         /* Tight loop containing cond_resched(). */
1813         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1814         cur_ops->sync(); /* Later readers see above write. */
1815         if  (selfpropcb) {
1816                 WRITE_ONCE(fcs.stop, 0);
1817                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1818         }
1819         cver = READ_ONCE(rcu_torture_current_version);
1820         gps = cur_ops->get_gp_seq();
1821         sd = cur_ops->stall_dur() + 1;
1822         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1823         dur = sd4 + torture_random(&trs) % (sd - sd4);
1824         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
1825         stopat = rfp->rcu_fwd_startat + dur;
1826         while (time_before(jiffies, stopat) &&
1827                !shutdown_time_arrived() &&
1828                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1829                 idx = cur_ops->readlock();
1830                 udelay(10);
1831                 cur_ops->readunlock(idx);
1832                 if (!fwd_progress_need_resched || need_resched())
1833                         cond_resched();
1834         }
1835         (*tested_tries)++;
1836         if (!time_before(jiffies, stopat) &&
1837             !shutdown_time_arrived() &&
1838             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1839                 (*tested)++;
1840                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1841                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1842                 WARN_ON(!cver && gps < 2);
1843                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1844         }
1845         if (selfpropcb) {
1846                 WRITE_ONCE(fcs.stop, 1);
1847                 cur_ops->sync(); /* Wait for running CB to complete. */
1848                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1849         }
1850
1851         if (selfpropcb) {
1852                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1853                 destroy_rcu_head_on_stack(&fcs.rh);
1854         }
1855         schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
1856         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1857 }
1858
1859 /* Carry out call_rcu() forward-progress testing. */
1860 static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
1861 {
1862         unsigned long cver;
1863         unsigned long flags;
1864         unsigned long gps;
1865         int i;
1866         long n_launders;
1867         long n_launders_cb_snap;
1868         long n_launders_sa;
1869         long n_max_cbs;
1870         long n_max_gps;
1871         struct rcu_fwd_cb *rfcp;
1872         struct rcu_fwd_cb *rfcpn;
1873         unsigned long stopat;
1874         unsigned long stoppedat;
1875
1876         if (READ_ONCE(rcu_fwd_emergency_stop))
1877                 return; /* Get out of the way quickly, no GP wait! */
1878         if (!cur_ops->call)
1879                 return; /* Can't do call_rcu() fwd prog without ->call. */
1880
1881         /* Loop continuously posting RCU callbacks. */
1882         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1883         cur_ops->sync(); /* Later readers see above write. */
1884         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
1885         stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1886         n_launders = 0;
1887         rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
1888         n_launders_sa = 0;
1889         n_max_cbs = 0;
1890         n_max_gps = 0;
1891         for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
1892                 rfp->n_launders_hist[i].n_launders = 0;
1893         cver = READ_ONCE(rcu_torture_current_version);
1894         gps = cur_ops->get_gp_seq();
1895         rfp->rcu_launder_gp_seq_start = gps;
1896         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
1897         while (time_before(jiffies, stopat) &&
1898                !shutdown_time_arrived() &&
1899                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1900                 rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
1901                 rfcpn = NULL;
1902                 if (rfcp)
1903                         rfcpn = READ_ONCE(rfcp->rfc_next);
1904                 if (rfcpn) {
1905                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1906                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1907                                 break;
1908                         rfp->rcu_fwd_cb_head = rfcpn;
1909                         n_launders++;
1910                         n_launders_sa++;
1911                 } else {
1912                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1913                         if (WARN_ON_ONCE(!rfcp)) {
1914                                 schedule_timeout_interruptible(1);
1915                                 continue;
1916                         }
1917                         n_max_cbs++;
1918                         n_launders_sa = 0;
1919                         rfcp->rfc_gps = 0;
1920                         rfcp->rfc_rfp = rfp;
1921                 }
1922                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1923                 rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
1924                 if (tick_nohz_full_enabled()) {
1925                         local_irq_save(flags);
1926                         rcu_momentary_dyntick_idle();
1927                         local_irq_restore(flags);
1928                 }
1929         }
1930         stoppedat = jiffies;
1931         n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
1932         cver = READ_ONCE(rcu_torture_current_version) - cver;
1933         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1934         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1935         (void)rcu_torture_fwd_prog_cbfree(rfp);
1936
1937         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
1938             !shutdown_time_arrived()) {
1939                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1940                 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",
1941                          __func__,
1942                          stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
1943                          n_launders + n_max_cbs - n_launders_cb_snap,
1944                          n_launders, n_launders_sa,
1945                          n_max_gps, n_max_cbs, cver, gps);
1946                 rcu_torture_fwd_cb_hist(rfp);
1947         }
1948         schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
1949         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
1950         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1951 }
1952
1953
1954 /*
1955  * OOM notifier, but this only prints diagnostic information for the
1956  * current forward-progress test.
1957  */
1958 static int rcutorture_oom_notify(struct notifier_block *self,
1959                                  unsigned long notused, void *nfreed)
1960 {
1961         struct rcu_fwd *rfp = rcu_fwds;
1962
1963         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1964              __func__);
1965         rcu_torture_fwd_cb_hist(rfp);
1966         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
1967         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1968         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1969         pr_info("%s: Freed %lu RCU callbacks.\n",
1970                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
1971         rcu_barrier();
1972         pr_info("%s: Freed %lu RCU callbacks.\n",
1973                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
1974         rcu_barrier();
1975         pr_info("%s: Freed %lu RCU callbacks.\n",
1976                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
1977         smp_mb(); /* Frees before return to avoid redoing OOM. */
1978         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1979         pr_info("%s returning after OOM processing.\n", __func__);
1980         return NOTIFY_OK;
1981 }
1982
1983 static struct notifier_block rcutorture_oom_nb = {
1984         .notifier_call = rcutorture_oom_notify
1985 };
1986
1987 /* Carry out grace-period forward-progress testing. */
1988 static int rcu_torture_fwd_prog(void *args)
1989 {
1990         struct rcu_fwd *rfp = args;
1991         int tested = 0;
1992         int tested_tries = 0;
1993
1994         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1995         rcu_bind_current_to_nocb();
1996         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1997                 set_user_nice(current, MAX_NICE);
1998         do {
1999                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
2000                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
2001                 register_oom_notifier(&rcutorture_oom_nb);
2002                 if (!IS_ENABLED(CONFIG_TINY_RCU) ||
2003                     rcu_inkernel_boot_has_ended())
2004                         rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
2005                 if (rcu_inkernel_boot_has_ended())
2006                         rcu_torture_fwd_prog_cr(rfp);
2007                 unregister_oom_notifier(&rcutorture_oom_nb);
2008
2009                 /* Avoid slow periods, better to test when busy. */
2010                 stutter_wait("rcu_torture_fwd_prog");
2011         } while (!torture_must_stop());
2012         /* Short runs might not contain a valid forward-progress attempt. */
2013         WARN_ON(!tested && tested_tries >= 5);
2014         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
2015         torture_kthread_stopping("rcu_torture_fwd_prog");
2016         return 0;
2017 }
2018
2019 /* If forward-progress checking is requested and feasible, spawn the thread. */
2020 static int __init rcu_torture_fwd_prog_init(void)
2021 {
2022         struct rcu_fwd *rfp;
2023
2024         if (!fwd_progress)
2025                 return 0; /* Not requested, so don't do it. */
2026         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
2027             cur_ops == &rcu_busted_ops) {
2028                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
2029                 return 0;
2030         }
2031         if (stall_cpu > 0) {
2032                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
2033                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
2034                         return -EINVAL; /* In module, can fail back to user. */
2035                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
2036                 return 0;
2037         }
2038         if (fwd_progress_holdoff <= 0)
2039                 fwd_progress_holdoff = 1;
2040         if (fwd_progress_div <= 0)
2041                 fwd_progress_div = 4;
2042         rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
2043         if (!rfp)
2044                 return -ENOMEM;
2045         spin_lock_init(&rfp->rcu_fwd_lock);
2046         rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2047         return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
2048 }
2049
2050 /* Callback function for RCU barrier testing. */
2051 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2052 {
2053         atomic_inc(&barrier_cbs_invoked);
2054 }
2055
2056 /* IPI handler to get callback posted on desired CPU, if online. */
2057 static void rcu_torture_barrier1cb(void *rcu_void)
2058 {
2059         struct rcu_head *rhp = rcu_void;
2060
2061         cur_ops->call(rhp, rcu_torture_barrier_cbf);
2062 }
2063
2064 /* kthread function to register callbacks used to test RCU barriers. */
2065 static int rcu_torture_barrier_cbs(void *arg)
2066 {
2067         long myid = (long)arg;
2068         bool lastphase = 0;
2069         bool newphase;
2070         struct rcu_head rcu;
2071
2072         init_rcu_head_on_stack(&rcu);
2073         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2074         set_user_nice(current, MAX_NICE);
2075         do {
2076                 wait_event(barrier_cbs_wq[myid],
2077                            (newphase =
2078                             smp_load_acquire(&barrier_phase)) != lastphase ||
2079                            torture_must_stop());
2080                 lastphase = newphase;
2081                 if (torture_must_stop())
2082                         break;
2083                 /*
2084                  * The above smp_load_acquire() ensures barrier_phase load
2085                  * is ordered before the following ->call().
2086                  */
2087                 if (smp_call_function_single(myid, rcu_torture_barrier1cb,
2088                                              &rcu, 1)) {
2089                         // IPI failed, so use direct call from current CPU.
2090                         cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2091                 }
2092                 if (atomic_dec_and_test(&barrier_cbs_count))
2093                         wake_up(&barrier_wq);
2094         } while (!torture_must_stop());
2095         if (cur_ops->cb_barrier != NULL)
2096                 cur_ops->cb_barrier();
2097         destroy_rcu_head_on_stack(&rcu);
2098         torture_kthread_stopping("rcu_torture_barrier_cbs");
2099         return 0;
2100 }
2101
2102 /* kthread function to drive and coordinate RCU barrier testing. */
2103 static int rcu_torture_barrier(void *arg)
2104 {
2105         int i;
2106
2107         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2108         do {
2109                 atomic_set(&barrier_cbs_invoked, 0);
2110                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
2111                 /* Ensure barrier_phase ordered after prior assignments. */
2112                 smp_store_release(&barrier_phase, !barrier_phase);
2113                 for (i = 0; i < n_barrier_cbs; i++)
2114                         wake_up(&barrier_cbs_wq[i]);
2115                 wait_event(barrier_wq,
2116                            atomic_read(&barrier_cbs_count) == 0 ||
2117                            torture_must_stop());
2118                 if (torture_must_stop())
2119                         break;
2120                 n_barrier_attempts++;
2121                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2122                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2123                         n_rcu_torture_barrier_error++;
2124                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2125                                atomic_read(&barrier_cbs_invoked),
2126                                n_barrier_cbs);
2127                         WARN_ON(1);
2128                         // Wait manually for the remaining callbacks
2129                         i = 0;
2130                         do {
2131                                 if (WARN_ON(i++ > HZ))
2132                                         i = INT_MIN;
2133                                 schedule_timeout_interruptible(1);
2134                                 cur_ops->cb_barrier();
2135                         } while (atomic_read(&barrier_cbs_invoked) !=
2136                                  n_barrier_cbs &&
2137                                  !torture_must_stop());
2138                         smp_mb(); // Can't trust ordering if broken.
2139                         if (!torture_must_stop())
2140                                 pr_err("Recovered: barrier_cbs_invoked = %d\n",
2141                                        atomic_read(&barrier_cbs_invoked));
2142                 } else {
2143                         n_barrier_successes++;
2144                 }
2145                 schedule_timeout_interruptible(HZ / 10);
2146         } while (!torture_must_stop());
2147         torture_kthread_stopping("rcu_torture_barrier");
2148         return 0;
2149 }
2150
2151 /* Initialize RCU barrier testing. */
2152 static int rcu_torture_barrier_init(void)
2153 {
2154         int i;
2155         int ret;
2156
2157         if (n_barrier_cbs <= 0)
2158                 return 0;
2159         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2160                 pr_alert("%s" TORTURE_FLAG
2161                          " Call or barrier ops missing for %s,\n",
2162                          torture_type, cur_ops->name);
2163                 pr_alert("%s" TORTURE_FLAG
2164                          " RCU barrier testing omitted from run.\n",
2165                          torture_type);
2166                 return 0;
2167         }
2168         atomic_set(&barrier_cbs_count, 0);
2169         atomic_set(&barrier_cbs_invoked, 0);
2170         barrier_cbs_tasks =
2171                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2172                         GFP_KERNEL);
2173         barrier_cbs_wq =
2174                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2175         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2176                 return -ENOMEM;
2177         for (i = 0; i < n_barrier_cbs; i++) {
2178                 init_waitqueue_head(&barrier_cbs_wq[i]);
2179                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2180                                              (void *)(long)i,
2181                                              barrier_cbs_tasks[i]);
2182                 if (ret)
2183                         return ret;
2184         }
2185         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2186 }
2187
2188 /* Clean up after RCU barrier testing. */
2189 static void rcu_torture_barrier_cleanup(void)
2190 {
2191         int i;
2192
2193         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2194         if (barrier_cbs_tasks != NULL) {
2195                 for (i = 0; i < n_barrier_cbs; i++)
2196                         torture_stop_kthread(rcu_torture_barrier_cbs,
2197                                              barrier_cbs_tasks[i]);
2198                 kfree(barrier_cbs_tasks);
2199                 barrier_cbs_tasks = NULL;
2200         }
2201         if (barrier_cbs_wq != NULL) {
2202                 kfree(barrier_cbs_wq);
2203                 barrier_cbs_wq = NULL;
2204         }
2205 }
2206
2207 static bool rcu_torture_can_boost(void)
2208 {
2209         static int boost_warn_once;
2210         int prio;
2211
2212         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2213                 return false;
2214
2215         prio = rcu_get_gp_kthreads_prio();
2216         if (!prio)
2217                 return false;
2218
2219         if (prio < 2) {
2220                 if (boost_warn_once  == 1)
2221                         return false;
2222
2223                 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);
2224                 boost_warn_once = 1;
2225                 return false;
2226         }
2227
2228         return true;
2229 }
2230
2231 static enum cpuhp_state rcutor_hp;
2232
2233 static void
2234 rcu_torture_cleanup(void)
2235 {
2236         int firsttime;
2237         int flags = 0;
2238         unsigned long gp_seq = 0;
2239         int i;
2240
2241         if (torture_cleanup_begin()) {
2242                 if (cur_ops->cb_barrier != NULL)
2243                         cur_ops->cb_barrier();
2244                 return;
2245         }
2246         if (!cur_ops) {
2247                 torture_cleanup_end();
2248                 return;
2249         }
2250
2251         show_rcu_gp_kthreads();
2252         rcu_torture_barrier_cleanup();
2253         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2254         torture_stop_kthread(rcu_torture_stall, stall_task);
2255         torture_stop_kthread(rcu_torture_writer, writer_task);
2256
2257         if (reader_tasks) {
2258                 for (i = 0; i < nrealreaders; i++)
2259                         torture_stop_kthread(rcu_torture_reader,
2260                                              reader_tasks[i]);
2261                 kfree(reader_tasks);
2262         }
2263         rcu_torture_current = NULL;
2264
2265         if (fakewriter_tasks) {
2266                 for (i = 0; i < nfakewriters; i++) {
2267                         torture_stop_kthread(rcu_torture_fakewriter,
2268                                              fakewriter_tasks[i]);
2269                 }
2270                 kfree(fakewriter_tasks);
2271                 fakewriter_tasks = NULL;
2272         }
2273
2274         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2275         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2276         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2277                  cur_ops->name, gp_seq, flags);
2278         torture_stop_kthread(rcu_torture_stats, stats_task);
2279         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2280         if (rcu_torture_can_boost())
2281                 cpuhp_remove_state(rcutor_hp);
2282
2283         /*
2284          * Wait for all RCU callbacks to fire, then do torture-type-specific
2285          * cleanup operations.
2286          */
2287         if (cur_ops->cb_barrier != NULL)
2288                 cur_ops->cb_barrier();
2289         if (cur_ops->cleanup != NULL)
2290                 cur_ops->cleanup();
2291
2292         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2293
2294         if (err_segs_recorded) {
2295                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2296                 if (rt_read_nsegs == 0)
2297                         pr_alert("\t: No segments recorded!!!\n");
2298                 firsttime = 1;
2299                 for (i = 0; i < rt_read_nsegs; i++) {
2300                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2301                         if (err_segs[i].rt_delay_jiffies != 0) {
2302                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2303                                         err_segs[i].rt_delay_jiffies);
2304                                 firsttime = 0;
2305                         }
2306                         if (err_segs[i].rt_delay_ms != 0) {
2307                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2308                                         err_segs[i].rt_delay_ms);
2309                                 firsttime = 0;
2310                         }
2311                         if (err_segs[i].rt_delay_us != 0) {
2312                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2313                                         err_segs[i].rt_delay_us);
2314                                 firsttime = 0;
2315                         }
2316                         pr_cont("%s\n",
2317                                 err_segs[i].rt_preempted ? "preempted" : "");
2318
2319                 }
2320         }
2321         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2322                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2323         else if (torture_onoff_failures())
2324                 rcu_torture_print_module_parms(cur_ops,
2325                                                "End of test: RCU_HOTPLUG");
2326         else
2327                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2328         torture_cleanup_end();
2329 }
2330
2331 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2332 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2333 {
2334 }
2335
2336 static void rcu_torture_err_cb(struct rcu_head *rhp)
2337 {
2338         /*
2339          * This -might- happen due to race conditions, but is unlikely.
2340          * The scenario that leads to this happening is that the
2341          * first of the pair of duplicate callbacks is queued,
2342          * someone else starts a grace period that includes that
2343          * callback, then the second of the pair must wait for the
2344          * next grace period.  Unlikely, but can happen.  If it
2345          * does happen, the debug-objects subsystem won't have splatted.
2346          */
2347         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2348 }
2349 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2350
2351 /*
2352  * Verify that double-free causes debug-objects to complain, but only
2353  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2354  * cannot be carried out.
2355  */
2356 static void rcu_test_debug_objects(void)
2357 {
2358 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2359         struct rcu_head rh1;
2360         struct rcu_head rh2;
2361
2362         init_rcu_head_on_stack(&rh1);
2363         init_rcu_head_on_stack(&rh2);
2364         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2365
2366         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2367         preempt_disable(); /* Prevent preemption from interrupting test. */
2368         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2369         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2370         local_irq_disable(); /* Make it harder to start a new grace period. */
2371         call_rcu(&rh2, rcu_torture_leak_cb);
2372         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2373         local_irq_enable();
2374         rcu_read_unlock();
2375         preempt_enable();
2376
2377         /* Wait for them all to get done so we can safely return. */
2378         rcu_barrier();
2379         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2380         destroy_rcu_head_on_stack(&rh1);
2381         destroy_rcu_head_on_stack(&rh2);
2382 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2383         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2384 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2385 }
2386
2387 static void rcutorture_sync(void)
2388 {
2389         static unsigned long n;
2390
2391         if (cur_ops->sync && !(++n & 0xfff))
2392                 cur_ops->sync();
2393 }
2394
2395 static int __init
2396 rcu_torture_init(void)
2397 {
2398         long i;
2399         int cpu;
2400         int firsterr = 0;
2401         static struct rcu_torture_ops *torture_ops[] = {
2402                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2403                 &busted_srcud_ops, &tasks_ops, &trivial_ops,
2404         };
2405
2406         if (!torture_init_begin(torture_type, verbose))
2407                 return -EBUSY;
2408
2409         /* Process args and tell the world that the torturer is on the job. */
2410         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2411                 cur_ops = torture_ops[i];
2412                 if (strcmp(torture_type, cur_ops->name) == 0)
2413                         break;
2414         }
2415         if (i == ARRAY_SIZE(torture_ops)) {
2416                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2417                          torture_type);
2418                 pr_alert("rcu-torture types:");
2419                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2420                         pr_cont(" %s", torture_ops[i]->name);
2421                 pr_cont("\n");
2422                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2423                 firsterr = -EINVAL;
2424                 cur_ops = NULL;
2425                 goto unwind;
2426         }
2427         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2428                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2429                 fqs_duration = 0;
2430         }
2431         if (cur_ops->init)
2432                 cur_ops->init();
2433
2434         if (nreaders >= 0) {
2435                 nrealreaders = nreaders;
2436         } else {
2437                 nrealreaders = num_online_cpus() - 2 - nreaders;
2438                 if (nrealreaders <= 0)
2439                         nrealreaders = 1;
2440         }
2441         rcu_torture_print_module_parms(cur_ops, "Start of test");
2442
2443         /* Set up the freelist. */
2444
2445         INIT_LIST_HEAD(&rcu_torture_freelist);
2446         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2447                 rcu_tortures[i].rtort_mbtest = 0;
2448                 list_add_tail(&rcu_tortures[i].rtort_free,
2449                               &rcu_torture_freelist);
2450         }
2451
2452         /* Initialize the statistics so that each run gets its own numbers. */
2453
2454         rcu_torture_current = NULL;
2455         rcu_torture_current_version = 0;
2456         atomic_set(&n_rcu_torture_alloc, 0);
2457         atomic_set(&n_rcu_torture_alloc_fail, 0);
2458         atomic_set(&n_rcu_torture_free, 0);
2459         atomic_set(&n_rcu_torture_mberror, 0);
2460         atomic_set(&n_rcu_torture_error, 0);
2461         n_rcu_torture_barrier_error = 0;
2462         n_rcu_torture_boost_ktrerror = 0;
2463         n_rcu_torture_boost_rterror = 0;
2464         n_rcu_torture_boost_failure = 0;
2465         n_rcu_torture_boosts = 0;
2466         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2467                 atomic_set(&rcu_torture_wcount[i], 0);
2468         for_each_possible_cpu(cpu) {
2469                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2470                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2471                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2472                 }
2473         }
2474         err_segs_recorded = 0;
2475         rt_read_nsegs = 0;
2476
2477         /* Start up the kthreads. */
2478
2479         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2480                                           writer_task);
2481         if (firsterr)
2482                 goto unwind;
2483         if (nfakewriters > 0) {
2484                 fakewriter_tasks = kcalloc(nfakewriters,
2485                                            sizeof(fakewriter_tasks[0]),
2486                                            GFP_KERNEL);
2487                 if (fakewriter_tasks == NULL) {
2488                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2489                         firsterr = -ENOMEM;
2490                         goto unwind;
2491                 }
2492         }
2493         for (i = 0; i < nfakewriters; i++) {
2494                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2495                                                   NULL, fakewriter_tasks[i]);
2496                 if (firsterr)
2497                         goto unwind;
2498         }
2499         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2500                                GFP_KERNEL);
2501         if (reader_tasks == NULL) {
2502                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2503                 firsterr = -ENOMEM;
2504                 goto unwind;
2505         }
2506         for (i = 0; i < nrealreaders; i++) {
2507                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2508                                                   reader_tasks[i]);
2509                 if (firsterr)
2510                         goto unwind;
2511         }
2512         if (stat_interval > 0) {
2513                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2514                                                   stats_task);
2515                 if (firsterr)
2516                         goto unwind;
2517         }
2518         if (test_no_idle_hz && shuffle_interval > 0) {
2519                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2520                 if (firsterr)
2521                         goto unwind;
2522         }
2523         if (stutter < 0)
2524                 stutter = 0;
2525         if (stutter) {
2526                 int t;
2527
2528                 t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
2529                 firsterr = torture_stutter_init(stutter * HZ, t);
2530                 if (firsterr)
2531                         goto unwind;
2532         }
2533         if (fqs_duration < 0)
2534                 fqs_duration = 0;
2535         if (fqs_duration) {
2536                 /* Create the fqs thread */
2537                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2538                                                   fqs_task);
2539                 if (firsterr)
2540                         goto unwind;
2541         }
2542         if (test_boost_interval < 1)
2543                 test_boost_interval = 1;
2544         if (test_boost_duration < 2)
2545                 test_boost_duration = 2;
2546         if (rcu_torture_can_boost()) {
2547
2548                 boost_starttime = jiffies + test_boost_interval * HZ;
2549
2550                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2551                                              rcutorture_booster_init,
2552                                              rcutorture_booster_cleanup);
2553                 if (firsterr < 0)
2554                         goto unwind;
2555                 rcutor_hp = firsterr;
2556         }
2557         shutdown_jiffies = jiffies + shutdown_secs * HZ;
2558         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2559         if (firsterr)
2560                 goto unwind;
2561         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2562                                       rcutorture_sync);
2563         if (firsterr)
2564                 goto unwind;
2565         firsterr = rcu_torture_stall_init();
2566         if (firsterr)
2567                 goto unwind;
2568         firsterr = rcu_torture_fwd_prog_init();
2569         if (firsterr)
2570                 goto unwind;
2571         firsterr = rcu_torture_barrier_init();
2572         if (firsterr)
2573                 goto unwind;
2574         if (object_debug)
2575                 rcu_test_debug_objects();
2576         torture_init_end();
2577         return 0;
2578
2579 unwind:
2580         torture_init_end();
2581         rcu_torture_cleanup();
2582         return firsterr;
2583 }
2584
2585 module_init(rcu_torture_init);
2586 module_exit(rcu_torture_cleanup);