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