kernel/rcu/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <[email protected]>
  21  *        Josh Triplett <[email protected]>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25
  26 #define pr_fmt(fmt) fmt
  27
  28 #include <linux/types.h>
  29 #include <linux/kernel.h>
  30 #include <linux/init.h>
  31 #include <linux/module.h>
  32 #include <linux/kthread.h>
  33 #include <linux/err.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/smp.h>
  36 #include <linux/rcupdate.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/sched/signal.h>
  39 #include <uapi/linux/sched/types.h>
  40 #include <linux/atomic.h>
  41 #include <linux/bitops.h>
  42 #include <linux/completion.h>
  43 #include <linux/moduleparam.h>
  44 #include <linux/percpu.h>
  45 #include <linux/notifier.h>
  46 #include <linux/reboot.h>
  47 #include <linux/freezer.h>
  48 #include <linux/cpu.h>
  49 #include <linux/delay.h>
  50 #include <linux/stat.h>
  51 #include <linux/srcu.h>
  52 #include <linux/slab.h>
  53 #include <linux/trace_clock.h>
  54 #include <asm/byteorder.h>
  55 #include <linux/torture.h>
  56 #include <linux/vmalloc.h>
  57 #include <linux/sched/debug.h>
  58 #include <linux/sched/sysctl.h>
  59
  60 #include "rcu.h"
  61
  62 MODULE_LICENSE("GPL");
  63 MODULE_AUTHOR("Paul E. McKenney <[email protected]> and Josh Triplett <[email protected]>");
  64
  65
  66 /* Bits for ->extendables field, extendables param, and related definitions. */
  67 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  68 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  69 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  70 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  71 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  72 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  73 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  74 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  75 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  76 #define RCUTORTURE_MAX_EXTEND    \
  77         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  78          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  79 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  80                                         /* Must be power of two minus one. */
  81 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  82
  83 torture_param(int, cbflood_inter_holdoff, HZ,
  84               "Holdoff between floods (jiffies)");
  85 torture_param(int, cbflood_intra_holdoff, 1,
  86               "Holdoff between bursts (jiffies)");
  87 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  88 torture_param(int, cbflood_n_per_burst, 20000,
  89               "# callbacks per burst in flood");
  90 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  91               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  92 torture_param(int, fqs_duration, 0,
  93               "Duration of fqs bursts (us), 0 to disable");
  94 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  95 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  96 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  97 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  98 torture_param(int, fwd_progress_holdoff, 60,
  99               "Time between forward-progress tests (s)");
 100 torture_param(bool, fwd_progress_need_resched, 1,
 101               "Hide cond_resched() behind need_resched()");
 102 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
 103 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
 104 torture_param(bool, gp_normal, false,
 105              "Use normal (non-expedited) GP wait primitives");
 106 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
 107 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
 108 torture_param(int, n_barrier_cbs, 0,
 109              "# of callbacks/kthreads for barrier testing");
 110 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
 111 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 112 torture_param(int, object_debug, 0,
 113              "Enable debug-object double call_rcu() testing");
 114 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
 115 torture_param(int, onoff_interval, 0,
 116              "Time between CPU hotplugs (jiffies), 0=disable");
 117 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 118 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 119 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 120 torture_param(int, stall_cpu_holdoff, 10,
 121              "Time to wait before starting stall (s).");
 122 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 123 torture_param(int, stat_interval, 60,
 124              "Number of seconds between stats printk()s");
 125 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 126 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 127 torture_param(int, test_boost_duration, 4,
 128              "Duration of each boost test, seconds.");
 129 torture_param(int, test_boost_interval, 7,
 130              "Interval between boost tests, seconds.");
 131 torture_param(bool, test_no_idle_hz, true,
 132              "Test support for tickless idle CPUs");
 133 torture_param(int, verbose, 1,
 134              "Enable verbose debugging printk()s");
 135
 136 static char *torture_type = "rcu";
 137 module_param(torture_type, charp, 0444);
 138 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 139
 140 static int nrealreaders;
 141 static int ncbflooders;
 142 static struct task_struct *writer_task;
 143 static struct task_struct **fakewriter_tasks;
 144 static struct task_struct **reader_tasks;
 145 static struct task_struct *stats_task;
 146 static struct task_struct **cbflood_task;
 147 static struct task_struct *fqs_task;
 148 static struct task_struct *boost_tasks[NR_CPUS];
 149 static struct task_struct *stall_task;
 150 static struct task_struct *fwd_prog_task;
 151 static struct task_struct **barrier_cbs_tasks;
 152 static struct task_struct *barrier_task;
 153
 154 #define RCU_TORTURE_PIPE_LEN 10
 155
 156 struct rcu_torture {
 157         struct rcu_head rtort_rcu;
 158         int rtort_pipe_count;
 159         struct list_head rtort_free;
 160         int rtort_mbtest;
 161 };
 162
 163 static LIST_HEAD(rcu_torture_freelist);
 164 static struct rcu_torture __rcu *rcu_torture_current;
 165 static unsigned long rcu_torture_current_version;
 166 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 167 static DEFINE_SPINLOCK(rcu_torture_lock);
 168 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 169 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 170 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 171 static atomic_t n_rcu_torture_alloc;
 172 static atomic_t n_rcu_torture_alloc_fail;
 173 static atomic_t n_rcu_torture_free;
 174 static atomic_t n_rcu_torture_mberror;
 175 static atomic_t n_rcu_torture_error;
 176 static long n_rcu_torture_barrier_error;
 177 static long n_rcu_torture_boost_ktrerror;
 178 static long n_rcu_torture_boost_rterror;
 179 static long n_rcu_torture_boost_failure;
 180 static long n_rcu_torture_boosts;
 181 static atomic_long_t n_rcu_torture_timers;
 182 static long n_barrier_attempts;
 183 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 184 static atomic_long_t n_cbfloods;
 185 static struct list_head rcu_torture_removed;
 186
 187 static int rcu_torture_writer_state;
 188 #define RTWS_FIXED_DELAY        0
 189 #define RTWS_DELAY              1
 190 #define RTWS_REPLACE            2
 191 #define RTWS_DEF_FREE           3
 192 #define RTWS_EXP_SYNC           4
 193 #define RTWS_COND_GET           5
 194 #define RTWS_COND_SYNC          6
 195 #define RTWS_SYNC               7
 196 #define RTWS_STUTTER            8
 197 #define RTWS_STOPPING           9
 198 static const char * const rcu_torture_writer_state_names[] = {
 199         "RTWS_FIXED_DELAY",
 200         "RTWS_DELAY",
 201         "RTWS_REPLACE",
 202         "RTWS_DEF_FREE",
 203         "RTWS_EXP_SYNC",
 204         "RTWS_COND_GET",
 205         "RTWS_COND_SYNC",
 206         "RTWS_SYNC",
 207         "RTWS_STUTTER",
 208         "RTWS_STOPPING",
 209 };
 210
 211 /* Record reader segment types and duration for first failing read. */
 212 struct rt_read_seg {
 213         int rt_readstate;
 214         unsigned long rt_delay_jiffies;
 215         unsigned long rt_delay_ms;
 216         unsigned long rt_delay_us;
 217         bool rt_preempted;
 218 };
 219 static int err_segs_recorded;
 220 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 221 static int rt_read_nsegs;
 222
 223 static const char *rcu_torture_writer_state_getname(void)
 224 {
 225         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 226
 227         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 228                 return "???";
 229         return rcu_torture_writer_state_names[i];
 230 }
 231
 232 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 233 #define rcu_can_boost() 1
 234 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 235 #define rcu_can_boost() 0
 236 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 237
 238 #ifdef CONFIG_RCU_TRACE
 239 static u64 notrace rcu_trace_clock_local(void)
 240 {
 241         u64 ts = trace_clock_local();
 242
 243         (void)do_div(ts, NSEC_PER_USEC);
 244         return ts;
 245 }
 246 #else /* #ifdef CONFIG_RCU_TRACE */
 247 static u64 notrace rcu_trace_clock_local(void)
 248 {
 249         return 0ULL;
 250 }
 251 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 252
 253 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 254 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 255                                         /*  and boost task create/destroy. */
 256 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 257 static bool barrier_phase;              /* Test phase. */
 258 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 259 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 260 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 261
 262 /*
 263  * Allocate an element from the rcu_tortures pool.
 264  */
 265 static struct rcu_torture *
 266 rcu_torture_alloc(void)
 267 {
 268         struct list_head *p;
 269
 270         spin_lock_bh(&rcu_torture_lock);
 271         if (list_empty(&rcu_torture_freelist)) {
 272                 atomic_inc(&n_rcu_torture_alloc_fail);
 273                 spin_unlock_bh(&rcu_torture_lock);
 274                 return NULL;
 275         }
 276         atomic_inc(&n_rcu_torture_alloc);
 277         p = rcu_torture_freelist.next;
 278         list_del_init(p);
 279         spin_unlock_bh(&rcu_torture_lock);
 280         return container_of(p, struct rcu_torture, rtort_free);
 281 }
 282
 283 /*
 284  * Free an element to the rcu_tortures pool.
 285  */
 286 static void
 287 rcu_torture_free(struct rcu_torture *p)
 288 {
 289         atomic_inc(&n_rcu_torture_free);
 290         spin_lock_bh(&rcu_torture_lock);
 291         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 292         spin_unlock_bh(&rcu_torture_lock);
 293 }
 294
 295 /*
 296  * Operations vector for selecting different types of tests.
 297  */
 298
 299 struct rcu_torture_ops {
 300         int ttype;
 301         void (*init)(void);
 302         void (*cleanup)(void);
 303         int (*readlock)(void);
 304         void (*read_delay)(struct torture_random_state *rrsp,
 305                            struct rt_read_seg *rtrsp);
 306         void (*readunlock)(int idx);
 307         unsigned long (*get_gp_seq)(void);
 308         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 309         void (*deferred_free)(struct rcu_torture *p);
 310         void (*sync)(void);
 311         void (*exp_sync)(void);
 312         unsigned long (*get_state)(void);
 313         void (*cond_sync)(unsigned long oldstate);
 314         call_rcu_func_t call;
 315         void (*cb_barrier)(void);
 316         void (*fqs)(void);
 317         void (*stats)(void);
 318         int (*stall_dur)(void);
 319         int irq_capable;
 320         int can_boost;
 321         int extendables;
 322         int ext_irq_conflict;
 323         const char *name;
 324 };
 325
 326 static struct rcu_torture_ops *cur_ops;
 327
 328 /*
 329  * Definitions for rcu torture testing.
 330  */
 331
 332 static int rcu_torture_read_lock(void) __acquires(RCU)
 333 {
 334         rcu_read_lock();
 335         return 0;
 336 }
 337
 338 static void
 339 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 340 {
 341         unsigned long started;
 342         unsigned long completed;
 343         const unsigned long shortdelay_us = 200;
 344         unsigned long longdelay_ms = 300;
 345         unsigned long long ts;
 346
 347         /* We want a short delay sometimes to make a reader delay the grace
 348          * period, and we want a long delay occasionally to trigger
 349          * force_quiescent_state. */
 350
 351         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 352                 started = cur_ops->get_gp_seq();
 353                 ts = rcu_trace_clock_local();
 354                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 355                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 356                 mdelay(longdelay_ms);
 357                 rtrsp->rt_delay_ms = longdelay_ms;
 358                 completed = cur_ops->get_gp_seq();
 359                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 360                                           started, completed);
 361         }
 362         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 363                 udelay(shortdelay_us);
 364                 rtrsp->rt_delay_us = shortdelay_us;
 365         }
 366         if (!preempt_count() &&
 367             !(torture_random(rrsp) % (nrealreaders * 500))) {
 368                 torture_preempt_schedule();  /* QS only if preemptible. */
 369                 rtrsp->rt_preempted = true;
 370         }
 371 }
 372
 373 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 374 {
 375         rcu_read_unlock();
 376 }
 377
 378 /*
 379  * Update callback in the pipe.  This should be invoked after a grace period.
 380  */
 381 static bool
 382 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 383 {
 384         int i;
 385
 386         i = rp->rtort_pipe_count;
 387         if (i > RCU_TORTURE_PIPE_LEN)
 388                 i = RCU_TORTURE_PIPE_LEN;
 389         atomic_inc(&rcu_torture_wcount[i]);
 390         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 391                 rp->rtort_mbtest = 0;
 392                 return true;
 393         }
 394         return false;
 395 }
 396
 397 /*
 398  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 399  * primitives.
 400  */
 401 static void
 402 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 403 {
 404         struct rcu_torture *rp;
 405         struct rcu_torture *rp1;
 406
 407         if (old_rp)
 408                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 409         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 410                 if (rcu_torture_pipe_update_one(rp)) {
 411                         list_del(&rp->rtort_free);
 412                         rcu_torture_free(rp);
 413                 }
 414         }
 415 }
 416
 417 static void
 418 rcu_torture_cb(struct rcu_head *p)
 419 {
 420         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 421
 422         if (torture_must_stop_irq()) {
 423                 /* Test is ending, just drop callbacks on the floor. */
 424                 /* The next initialization will pick up the pieces. */
 425                 return;
 426         }
 427         if (rcu_torture_pipe_update_one(rp))
 428                 rcu_torture_free(rp);
 429         else
 430                 cur_ops->deferred_free(rp);
 431 }
 432
 433 static unsigned long rcu_no_completed(void)
 434 {
 435         return 0;
 436 }
 437
 438 static void rcu_torture_deferred_free(struct rcu_torture *p)
 439 {
 440         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 441 }
 442
 443 static void rcu_sync_torture_init(void)
 444 {
 445         INIT_LIST_HEAD(&rcu_torture_removed);
 446 }
 447
 448 static struct rcu_torture_ops rcu_ops = {
 449         .ttype          = RCU_FLAVOR,
 450         .init           = rcu_sync_torture_init,
 451         .readlock       = rcu_torture_read_lock,
 452         .read_delay     = rcu_read_delay,
 453         .readunlock     = rcu_torture_read_unlock,
 454         .get_gp_seq     = rcu_get_gp_seq,
 455         .gp_diff        = rcu_seq_diff,
 456         .deferred_free  = rcu_torture_deferred_free,
 457         .sync           = synchronize_rcu,
 458         .exp_sync       = synchronize_rcu_expedited,
 459         .get_state      = get_state_synchronize_rcu,
 460         .cond_sync      = cond_synchronize_rcu,
 461         .call           = call_rcu,
 462         .cb_barrier     = rcu_barrier,
 463         .fqs            = rcu_force_quiescent_state,
 464         .stats          = NULL,
 465         .stall_dur      = rcu_jiffies_till_stall_check,
 466         .irq_capable    = 1,
 467         .can_boost      = rcu_can_boost(),
 468         .extendables    = RCUTORTURE_MAX_EXTEND,
 469         .name           = "rcu"
 470 };
 471
 472 /*
 473  * Don't even think about trying any of these in real life!!!
 474  * The names includes "busted", and they really means it!
 475  * The only purpose of these functions is to provide a buggy RCU
 476  * implementation to make sure that rcutorture correctly emits
 477  * buggy-RCU error messages.
 478  */
 479 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 480 {
 481         /* This is a deliberate bug for testing purposes only! */
 482         rcu_torture_cb(&p->rtort_rcu);
 483 }
 484
 485 static void synchronize_rcu_busted(void)
 486 {
 487         /* This is a deliberate bug for testing purposes only! */
 488 }
 489
 490 static void
 491 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 492 {
 493         /* This is a deliberate bug for testing purposes only! */
 494         func(head);
 495 }
 496
 497 static struct rcu_torture_ops rcu_busted_ops = {
 498         .ttype          = INVALID_RCU_FLAVOR,
 499         .init           = rcu_sync_torture_init,
 500         .readlock       = rcu_torture_read_lock,
 501         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 502         .readunlock     = rcu_torture_read_unlock,
 503         .get_gp_seq     = rcu_no_completed,
 504         .deferred_free  = rcu_busted_torture_deferred_free,
 505         .sync           = synchronize_rcu_busted,
 506         .exp_sync       = synchronize_rcu_busted,
 507         .call           = call_rcu_busted,
 508         .cb_barrier     = NULL,
 509         .fqs            = NULL,
 510         .stats          = NULL,
 511         .irq_capable    = 1,
 512         .name           = "busted"
 513 };
 514
 515 /*
 516  * Definitions for srcu torture testing.
 517  */
 518
 519 DEFINE_STATIC_SRCU(srcu_ctl);
 520 static struct srcu_struct srcu_ctld;
 521 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 522
 523 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 524 {
 525         return srcu_read_lock(srcu_ctlp);
 526 }
 527
 528 static void
 529 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 530 {
 531         long delay;
 532         const long uspertick = 1000000 / HZ;
 533         const long longdelay = 10;
 534
 535         /* We want there to be long-running readers, but not all the time. */
 536
 537         delay = torture_random(rrsp) %
 538                 (nrealreaders * 2 * longdelay * uspertick);
 539         if (!delay && in_task()) {
 540                 schedule_timeout_interruptible(longdelay);
 541                 rtrsp->rt_delay_jiffies = longdelay;
 542         } else {
 543                 rcu_read_delay(rrsp, rtrsp);
 544         }
 545 }
 546
 547 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 548 {
 549         srcu_read_unlock(srcu_ctlp, idx);
 550 }
 551
 552 static unsigned long srcu_torture_completed(void)
 553 {
 554         return srcu_batches_completed(srcu_ctlp);
 555 }
 556
 557 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 558 {
 559         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 560 }
 561
 562 static void srcu_torture_synchronize(void)
 563 {
 564         synchronize_srcu(srcu_ctlp);
 565 }
 566
 567 static void srcu_torture_call(struct rcu_head *head,
 568                               rcu_callback_t func)
 569 {
 570         call_srcu(srcu_ctlp, head, func);
 571 }
 572
 573 static void srcu_torture_barrier(void)
 574 {
 575         srcu_barrier(srcu_ctlp);
 576 }
 577
 578 static void srcu_torture_stats(void)
 579 {
 580         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 581 }
 582
 583 static void srcu_torture_synchronize_expedited(void)
 584 {
 585         synchronize_srcu_expedited(srcu_ctlp);
 586 }
 587
 588 static struct rcu_torture_ops srcu_ops = {
 589         .ttype          = SRCU_FLAVOR,
 590         .init           = rcu_sync_torture_init,
 591         .readlock       = srcu_torture_read_lock,
 592         .read_delay     = srcu_read_delay,
 593         .readunlock     = srcu_torture_read_unlock,
 594         .get_gp_seq     = srcu_torture_completed,
 595         .deferred_free  = srcu_torture_deferred_free,
 596         .sync           = srcu_torture_synchronize,
 597         .exp_sync       = srcu_torture_synchronize_expedited,
 598         .call           = srcu_torture_call,
 599         .cb_barrier     = srcu_torture_barrier,
 600         .stats          = srcu_torture_stats,
 601         .irq_capable    = 1,
 602         .name           = "srcu"
 603 };
 604
 605 static void srcu_torture_init(void)
 606 {
 607         rcu_sync_torture_init();
 608         WARN_ON(init_srcu_struct(&srcu_ctld));
 609         srcu_ctlp = &srcu_ctld;
 610 }
 611
 612 static void srcu_torture_cleanup(void)
 613 {
 614         static DEFINE_TORTURE_RANDOM(rand);
 615
 616         if (torture_random(&rand) & 0x800)
 617                 cleanup_srcu_struct(&srcu_ctld);
 618         else
 619                 cleanup_srcu_struct_quiesced(&srcu_ctld);
 620         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 621 }
 622
 623 /* As above, but dynamically allocated. */
 624 static struct rcu_torture_ops srcud_ops = {
 625         .ttype          = SRCU_FLAVOR,
 626         .init           = srcu_torture_init,
 627         .cleanup        = srcu_torture_cleanup,
 628         .readlock       = srcu_torture_read_lock,
 629         .read_delay     = srcu_read_delay,
 630         .readunlock     = srcu_torture_read_unlock,
 631         .get_gp_seq     = srcu_torture_completed,
 632         .deferred_free  = srcu_torture_deferred_free,
 633         .sync           = srcu_torture_synchronize,
 634         .exp_sync       = srcu_torture_synchronize_expedited,
 635         .call           = srcu_torture_call,
 636         .cb_barrier     = srcu_torture_barrier,
 637         .stats          = srcu_torture_stats,
 638         .irq_capable    = 1,
 639         .name           = "srcud"
 640 };
 641
 642 /* As above, but broken due to inappropriate reader extension. */
 643 static struct rcu_torture_ops busted_srcud_ops = {
 644         .ttype          = SRCU_FLAVOR,
 645         .init           = srcu_torture_init,
 646         .cleanup        = srcu_torture_cleanup,
 647         .readlock       = srcu_torture_read_lock,
 648         .read_delay     = rcu_read_delay,
 649         .readunlock     = srcu_torture_read_unlock,
 650         .get_gp_seq     = srcu_torture_completed,
 651         .deferred_free  = srcu_torture_deferred_free,
 652         .sync           = srcu_torture_synchronize,
 653         .exp_sync       = srcu_torture_synchronize_expedited,
 654         .call           = srcu_torture_call,
 655         .cb_barrier     = srcu_torture_barrier,
 656         .stats          = srcu_torture_stats,
 657         .irq_capable    = 1,
 658         .extendables    = RCUTORTURE_MAX_EXTEND,
 659         .name           = "busted_srcud"
 660 };
 661
 662 /*
 663  * Definitions for RCU-tasks torture testing.
 664  */
 665
 666 static int tasks_torture_read_lock(void)
 667 {
 668         return 0;
 669 }
 670
 671 static void tasks_torture_read_unlock(int idx)
 672 {
 673 }
 674
 675 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 676 {
 677         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 678 }
 679
 680 static struct rcu_torture_ops tasks_ops = {
 681         .ttype          = RCU_TASKS_FLAVOR,
 682         .init           = rcu_sync_torture_init,
 683         .readlock       = tasks_torture_read_lock,
 684         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 685         .readunlock     = tasks_torture_read_unlock,
 686         .get_gp_seq     = rcu_no_completed,
 687         .deferred_free  = rcu_tasks_torture_deferred_free,
 688         .sync           = synchronize_rcu_tasks,
 689         .exp_sync       = synchronize_rcu_tasks,
 690         .call           = call_rcu_tasks,
 691         .cb_barrier     = rcu_barrier_tasks,
 692         .fqs            = NULL,
 693         .stats          = NULL,
 694         .irq_capable    = 1,
 695         .name           = "tasks"
 696 };
 697
 698 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 699 {
 700         if (!cur_ops->gp_diff)
 701                 return new - old;
 702         return cur_ops->gp_diff(new, old);
 703 }
 704
 705 static bool __maybe_unused torturing_tasks(void)
 706 {
 707         return cur_ops == &tasks_ops;
 708 }
 709
 710 /*
 711  * RCU torture priority-boost testing.  Runs one real-time thread per
 712  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 713  * spinning waiting for them to be invoked.  If a given callback takes
 714  * too long to be invoked, we assume that priority inversion has occurred.
 715  */
 716
 717 struct rcu_boost_inflight {
 718         struct rcu_head rcu;
 719         int inflight;
 720 };
 721
 722 static void rcu_torture_boost_cb(struct rcu_head *head)
 723 {
 724         struct rcu_boost_inflight *rbip =
 725                 container_of(head, struct rcu_boost_inflight, rcu);
 726
 727         /* Ensure RCU-core accesses precede clearing ->inflight */
 728         smp_store_release(&rbip->inflight, 0);
 729 }
 730
 731 static int old_rt_runtime = -1;
 732
 733 static void rcu_torture_disable_rt_throttle(void)
 734 {
 735         /*
 736          * Disable RT throttling so that rcutorture's boost threads don't get
 737          * throttled. Only possible if rcutorture is built-in otherwise the
 738          * user should manually do this by setting the sched_rt_period_us and
 739          * sched_rt_runtime sysctls.
 740          */
 741         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 742                 return;
 743
 744         old_rt_runtime = sysctl_sched_rt_runtime;
 745         sysctl_sched_rt_runtime = -1;
 746 }
 747
 748 static void rcu_torture_enable_rt_throttle(void)
 749 {
 750         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 751                 return;
 752
 753         sysctl_sched_rt_runtime = old_rt_runtime;
 754         old_rt_runtime = -1;
 755 }
 756
 757 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 758 {
 759         if (end - start > test_boost_duration * HZ - HZ / 2) {
 760                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 761                 n_rcu_torture_boost_failure++;
 762
 763                 return true; /* failed */
 764         }
 765
 766         return false; /* passed */
 767 }
 768
 769 static int rcu_torture_boost(void *arg)
 770 {
 771         unsigned long call_rcu_time;
 772         unsigned long endtime;
 773         unsigned long oldstarttime;
 774         struct rcu_boost_inflight rbi = { .inflight = 0 };
 775         struct sched_param sp;
 776
 777         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 778
 779         /* Set real-time priority. */
 780         sp.sched_priority = 1;
 781         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 782                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 783                 n_rcu_torture_boost_rterror++;
 784         }
 785
 786         init_rcu_head_on_stack(&rbi.rcu);
 787         /* Each pass through the following loop does one boost-test cycle. */
 788         do {
 789                 /* Track if the test failed already in this test interval? */
 790                 bool failed = false;
 791
 792                 /* Increment n_rcu_torture_boosts once per boost-test */
 793                 while (!kthread_should_stop()) {
 794                         if (mutex_trylock(&boost_mutex)) {
 795                                 n_rcu_torture_boosts++;
 796                                 mutex_unlock(&boost_mutex);
 797                                 break;
 798                         }
 799                         schedule_timeout_uninterruptible(1);
 800                 }
 801                 if (kthread_should_stop())
 802                         goto checkwait;
 803
 804                 /* Wait for the next test interval. */
 805                 oldstarttime = boost_starttime;
 806                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 807                         schedule_timeout_interruptible(oldstarttime - jiffies);
 808                         stutter_wait("rcu_torture_boost");
 809                         if (torture_must_stop())
 810                                 goto checkwait;
 811                 }
 812
 813                 /* Do one boost-test interval. */
 814                 endtime = oldstarttime + test_boost_duration * HZ;
 815                 call_rcu_time = jiffies;
 816                 while (ULONG_CMP_LT(jiffies, endtime)) {
 817                         /* If we don't have a callback in flight, post one. */
 818                         if (!smp_load_acquire(&rbi.inflight)) {
 819                                 /* RCU core before ->inflight = 1. */
 820                                 smp_store_release(&rbi.inflight, 1);
 821                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 822                                 /* Check if the boost test failed */
 823                                 failed = failed ||
 824                                          rcu_torture_boost_failed(call_rcu_time,
 825                                                                  jiffies);
 826                                 call_rcu_time = jiffies;
 827                         }
 828                         stutter_wait("rcu_torture_boost");
 829                         if (torture_must_stop())
 830                                 goto checkwait;
 831                 }
 832
 833                 /*
 834                  * If boost never happened, then inflight will always be 1, in
 835                  * this case the boost check would never happen in the above
 836                  * loop so do another one here.
 837                  */
 838                 if (!failed && smp_load_acquire(&rbi.inflight))
 839                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 840
 841                 /*
 842                  * Set the start time of the next test interval.
 843                  * Yes, this is vulnerable to long delays, but such
 844                  * delays simply cause a false negative for the next
 845                  * interval.  Besides, we are running at RT priority,
 846                  * so delays should be relatively rare.
 847                  */
 848                 while (oldstarttime == boost_starttime &&
 849                        !kthread_should_stop()) {
 850                         if (mutex_trylock(&boost_mutex)) {
 851                                 boost_starttime = jiffies +
 852                                                   test_boost_interval * HZ;
 853                                 mutex_unlock(&boost_mutex);
 854                                 break;
 855                         }
 856                         schedule_timeout_uninterruptible(1);
 857                 }
 858
 859                 /* Go do the stutter. */
 860 checkwait:      stutter_wait("rcu_torture_boost");
 861         } while (!torture_must_stop());
 862
 863         /* Clean up and exit. */
 864         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 865                 torture_shutdown_absorb("rcu_torture_boost");
 866                 schedule_timeout_uninterruptible(1);
 867         }
 868         destroy_rcu_head_on_stack(&rbi.rcu);
 869         torture_kthread_stopping("rcu_torture_boost");
 870         return 0;
 871 }
 872
 873 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 874 {
 875 }
 876
 877 /*
 878  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 879  * to call_rcu() or analogous, increasing the probability of occurrence
 880  * of callback-overflow corner cases.
 881  */
 882 static int
 883 rcu_torture_cbflood(void *arg)
 884 {
 885         int err = 1;
 886         int i;
 887         int j;
 888         struct rcu_head *rhp;
 889
 890         if (cbflood_n_per_burst > 0 &&
 891             cbflood_inter_holdoff > 0 &&
 892             cbflood_intra_holdoff > 0 &&
 893             cur_ops->call &&
 894             cur_ops->cb_barrier) {
 895                 rhp = vmalloc(array3_size(cbflood_n_burst,
 896                                           cbflood_n_per_burst,
 897                                           sizeof(*rhp)));
 898                 err = !rhp;
 899         }
 900         if (err) {
 901                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 902                 goto wait_for_stop;
 903         }
 904         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 905         do {
 906                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 907                 atomic_long_inc(&n_cbfloods);
 908                 WARN_ON(signal_pending(current));
 909                 for (i = 0; i < cbflood_n_burst; i++) {
 910                         for (j = 0; j < cbflood_n_per_burst; j++) {
 911                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 912                                               rcu_torture_cbflood_cb);
 913                         }
 914                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 915                         WARN_ON(signal_pending(current));
 916                 }
 917                 cur_ops->cb_barrier();
 918                 stutter_wait("rcu_torture_cbflood");
 919         } while (!torture_must_stop());
 920         vfree(rhp);
 921 wait_for_stop:
 922         torture_kthread_stopping("rcu_torture_cbflood");
 923         return 0;
 924 }
 925
 926 /*
 927  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 928  * bursts of calls to force_quiescent_state(), increasing the probability
 929  * of occurrence of some important types of race conditions.
 930  */
 931 static int
 932 rcu_torture_fqs(void *arg)
 933 {
 934         unsigned long fqs_resume_time;
 935         int fqs_burst_remaining;
 936
 937         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 938         do {
 939                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 940                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 941                        !kthread_should_stop()) {
 942                         schedule_timeout_interruptible(1);
 943                 }
 944                 fqs_burst_remaining = fqs_duration;
 945                 while (fqs_burst_remaining > 0 &&
 946                        !kthread_should_stop()) {
 947                         cur_ops->fqs();
 948                         udelay(fqs_holdoff);
 949                         fqs_burst_remaining -= fqs_holdoff;
 950                 }
 951                 stutter_wait("rcu_torture_fqs");
 952         } while (!torture_must_stop());
 953         torture_kthread_stopping("rcu_torture_fqs");
 954         return 0;
 955 }
 956
 957 /*
 958  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 959  * for that pointed to by rcu_torture_current, freeing the old structure
 960  * after a series of grace periods (the "pipeline").
 961  */
 962 static int
 963 rcu_torture_writer(void *arg)
 964 {
 965         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 966         int expediting = 0;
 967         unsigned long gp_snap;
 968         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 969         bool gp_sync1 = gp_sync;
 970         int i;
 971         struct rcu_torture *rp;
 972         struct rcu_torture *old_rp;
 973         static DEFINE_TORTURE_RANDOM(rand);
 974         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 975                            RTWS_COND_GET, RTWS_SYNC };
 976         int nsynctypes = 0;
 977
 978         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 979         if (!can_expedite)
 980                 pr_alert("%s" TORTURE_FLAG
 981                          " GP expediting controlled from boot/sysfs for %s.\n",
 982                          torture_type, cur_ops->name);
 983
 984         /* Initialize synctype[] array.  If none set, take default. */
 985         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 986                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 987         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 988                 synctype[nsynctypes++] = RTWS_COND_GET;
 989                 pr_info("%s: Testing conditional GPs.\n", __func__);
 990         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 991                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 992         }
 993         if (gp_exp1 && cur_ops->exp_sync) {
 994                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 995                 pr_info("%s: Testing expedited GPs.\n", __func__);
 996         } else if (gp_exp && !cur_ops->exp_sync) {
 997                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 998         }
 999         if (gp_normal1 && cur_ops->deferred_free) {
1000                 synctype[nsynctypes++] = RTWS_DEF_FREE;
1001                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
1002         } else if (gp_normal && !cur_ops->deferred_free) {
1003                 pr_alert("%s: gp_normal without primitives.\n", __func__);
1004         }
1005         if (gp_sync1 && cur_ops->sync) {
1006                 synctype[nsynctypes++] = RTWS_SYNC;
1007                 pr_info("%s: Testing normal GPs.\n", __func__);
1008         } else if (gp_sync && !cur_ops->sync) {
1009                 pr_alert("%s: gp_sync without primitives.\n", __func__);
1010         }
1011         if (WARN_ONCE(nsynctypes == 0,
1012                       "rcu_torture_writer: No update-side primitives.\n")) {
1013                 /*
1014                  * No updates primitives, so don't try updating.
1015                  * The resulting test won't be testing much, hence the
1016                  * above WARN_ONCE().
1017                  */
1018                 rcu_torture_writer_state = RTWS_STOPPING;
1019                 torture_kthread_stopping("rcu_torture_writer");
1020         }
1021
1022         do {
1023                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
1024                 schedule_timeout_uninterruptible(1);
1025                 rp = rcu_torture_alloc();
1026                 if (rp == NULL)
1027                         continue;
1028                 rp->rtort_pipe_count = 0;
1029                 rcu_torture_writer_state = RTWS_DELAY;
1030                 udelay(torture_random(&rand) & 0x3ff);
1031                 rcu_torture_writer_state = RTWS_REPLACE;
1032                 old_rp = rcu_dereference_check(rcu_torture_current,
1033                                                current == writer_task);
1034                 rp->rtort_mbtest = 1;
1035                 rcu_assign_pointer(rcu_torture_current, rp);
1036                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1037                 if (old_rp) {
1038                         i = old_rp->rtort_pipe_count;
1039                         if (i > RCU_TORTURE_PIPE_LEN)
1040                                 i = RCU_TORTURE_PIPE_LEN;
1041                         atomic_inc(&rcu_torture_wcount[i]);
1042                         old_rp->rtort_pipe_count++;
1043                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1044                         case RTWS_DEF_FREE:
1045                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1046                                 cur_ops->deferred_free(old_rp);
1047                                 break;
1048                         case RTWS_EXP_SYNC:
1049                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1050                                 cur_ops->exp_sync();
1051                                 rcu_torture_pipe_update(old_rp);
1052                                 break;
1053                         case RTWS_COND_GET:
1054                                 rcu_torture_writer_state = RTWS_COND_GET;
1055                                 gp_snap = cur_ops->get_state();
1056                                 i = torture_random(&rand) % 16;
1057                                 if (i != 0)
1058                                         schedule_timeout_interruptible(i);
1059                                 udelay(torture_random(&rand) % 1000);
1060                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1061                                 cur_ops->cond_sync(gp_snap);
1062                                 rcu_torture_pipe_update(old_rp);
1063                                 break;
1064                         case RTWS_SYNC:
1065                                 rcu_torture_writer_state = RTWS_SYNC;
1066                                 cur_ops->sync();
1067                                 rcu_torture_pipe_update(old_rp);
1068                                 break;
1069                         default:
1070                                 WARN_ON_ONCE(1);
1071                                 break;
1072                         }
1073                 }
1074                 WRITE_ONCE(rcu_torture_current_version,
1075                            rcu_torture_current_version + 1);
1076                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1077                 if (can_expedite &&
1078                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1079                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1080                         if (expediting >= 0)
1081                                 rcu_expedite_gp();
1082                         else
1083                                 rcu_unexpedite_gp();
1084                         if (++expediting > 3)
1085                                 expediting = -expediting;
1086                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1087                         can_expedite = !rcu_gp_is_expedited() &&
1088                                        !rcu_gp_is_normal();
1089                 }
1090                 rcu_torture_writer_state = RTWS_STUTTER;
1091                 if (stutter_wait("rcu_torture_writer"))
1092                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1093                                 if (list_empty(&rcu_tortures[i].rtort_free))
1094                                         WARN_ON_ONCE(1);
1095         } while (!torture_must_stop());
1096         /* Reset expediting back to unexpedited. */
1097         if (expediting > 0)
1098                 expediting = -expediting;
1099         while (can_expedite && expediting++ < 0)
1100                 rcu_unexpedite_gp();
1101         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1102         if (!can_expedite)
1103                 pr_alert("%s" TORTURE_FLAG
1104                          " Dynamic grace-period expediting was disabled.\n",
1105                          torture_type);
1106         rcu_torture_writer_state = RTWS_STOPPING;
1107         torture_kthread_stopping("rcu_torture_writer");
1108         return 0;
1109 }
1110
1111 /*
1112  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1113  * delay between calls.
1114  */
1115 static int
1116 rcu_torture_fakewriter(void *arg)
1117 {
1118         DEFINE_TORTURE_RANDOM(rand);
1119
1120         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1121         set_user_nice(current, MAX_NICE);
1122
1123         do {
1124                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1125                 udelay(torture_random(&rand) & 0x3ff);
1126                 if (cur_ops->cb_barrier != NULL &&
1127                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1128                         cur_ops->cb_barrier();
1129                 } else if (gp_normal == gp_exp) {
1130                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1131                                 cur_ops->sync();
1132                         else if (cur_ops->exp_sync)
1133                                 cur_ops->exp_sync();
1134                 } else if (gp_normal && cur_ops->sync) {
1135                         cur_ops->sync();
1136                 } else if (cur_ops->exp_sync) {
1137                         cur_ops->exp_sync();
1138                 }
1139                 stutter_wait("rcu_torture_fakewriter");
1140         } while (!torture_must_stop());
1141
1142         torture_kthread_stopping("rcu_torture_fakewriter");
1143         return 0;
1144 }
1145
1146 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1147 {
1148         kfree(rhp);
1149 }
1150
1151 /*
1152  * Do one extension of an RCU read-side critical section using the
1153  * current reader state in readstate (set to zero for initial entry
1154  * to extended critical section), set the new state as specified by
1155  * newstate (set to zero for final exit from extended critical section),
1156  * and random-number-generator state in trsp.  If this is neither the
1157  * beginning or end of the critical section and if there was actually a
1158  * change, do a ->read_delay().
1159  */
1160 static void rcutorture_one_extend(int *readstate, int newstate,
1161                                   struct torture_random_state *trsp,
1162                                   struct rt_read_seg *rtrsp)
1163 {
1164         int idxnew = -1;
1165         int idxold = *readstate;
1166         int statesnew = ~*readstate & newstate;
1167         int statesold = *readstate & ~newstate;
1168
1169         WARN_ON_ONCE(idxold < 0);
1170         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1171         rtrsp->rt_readstate = newstate;
1172
1173         /* First, put new protection in place to avoid critical-section gap. */
1174         if (statesnew & RCUTORTURE_RDR_BH)
1175                 local_bh_disable();
1176         if (statesnew & RCUTORTURE_RDR_IRQ)
1177                 local_irq_disable();
1178         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1179                 preempt_disable();
1180         if (statesnew & RCUTORTURE_RDR_RBH)
1181                 rcu_read_lock_bh();
1182         if (statesnew & RCUTORTURE_RDR_SCHED)
1183                 rcu_read_lock_sched();
1184         if (statesnew & RCUTORTURE_RDR_RCU)
1185                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1186
1187         /* Next, remove old protection, irq first due to bh conflict. */
1188         if (statesold & RCUTORTURE_RDR_IRQ)
1189                 local_irq_enable();
1190         if (statesold & RCUTORTURE_RDR_BH)
1191                 local_bh_enable();
1192         if (statesold & RCUTORTURE_RDR_PREEMPT)
1193                 preempt_enable();
1194         if (statesold & RCUTORTURE_RDR_RBH)
1195                 rcu_read_unlock_bh();
1196         if (statesold & RCUTORTURE_RDR_SCHED)
1197                 rcu_read_unlock_sched();
1198         if (statesold & RCUTORTURE_RDR_RCU)
1199                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1200
1201         /* Delay if neither beginning nor end and there was a change. */
1202         if ((statesnew || statesold) && *readstate && newstate)
1203                 cur_ops->read_delay(trsp, rtrsp);
1204
1205         /* Update the reader state. */
1206         if (idxnew == -1)
1207                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1208         WARN_ON_ONCE(idxnew < 0);
1209         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1210         *readstate = idxnew | newstate;
1211         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1212         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1213 }
1214
1215 /* Return the biggest extendables mask given current RCU and boot parameters. */
1216 static int rcutorture_extend_mask_max(void)
1217 {
1218         int mask;
1219
1220         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1221         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1222         mask = mask | RCUTORTURE_RDR_RCU;
1223         return mask;
1224 }
1225
1226 /* Return a random protection state mask, but with at least one bit set. */
1227 static int
1228 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1229 {
1230         int mask = rcutorture_extend_mask_max();
1231         unsigned long randmask1 = torture_random(trsp) >> 8;
1232         unsigned long randmask2 = randmask1 >> 3;
1233
1234         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1235         /* Most of the time lots of bits, half the time only one bit. */
1236         if (!(randmask1 & 0x7))
1237                 mask = mask & randmask2;
1238         else
1239                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1240         /* Can't enable bh w/irq disabled. */
1241         if ((mask & RCUTORTURE_RDR_IRQ) &&
1242             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1243              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1244                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1245         if ((mask & RCUTORTURE_RDR_IRQ) &&
1246             !(mask & cur_ops->ext_irq_conflict) &&
1247             (oldmask & cur_ops->ext_irq_conflict))
1248                 mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
1249         return mask ?: RCUTORTURE_RDR_RCU;
1250 }
1251
1252 /*
1253  * Do a randomly selected number of extensions of an existing RCU read-side
1254  * critical section.
1255  */
1256 static struct rt_read_seg *
1257 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1258                        struct rt_read_seg *rtrsp)
1259 {
1260         int i;
1261         int j;
1262         int mask = rcutorture_extend_mask_max();
1263
1264         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1265         if (!((mask - 1) & mask))
1266                 return rtrsp;  /* Current RCU reader not extendable. */
1267         /* Bias towards larger numbers of loops. */
1268         i = (torture_random(trsp) >> 3);
1269         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1270         for (j = 0; j < i; j++) {
1271                 mask = rcutorture_extend_mask(*readstate, trsp);
1272                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1273         }
1274         return &rtrsp[j];
1275 }
1276
1277 /*
1278  * Do one read-side critical section, returning false if there was
1279  * no data to read.  Can be invoked both from process context and
1280  * from a timer handler.
1281  */
1282 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1283 {
1284         int i;
1285         unsigned long started;
1286         unsigned long completed;
1287         int newstate;
1288         struct rcu_torture *p;
1289         int pipe_count;
1290         int readstate = 0;
1291         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1292         struct rt_read_seg *rtrsp = &rtseg[0];
1293         struct rt_read_seg *rtrsp1;
1294         unsigned long long ts;
1295
1296         newstate = rcutorture_extend_mask(readstate, trsp);
1297         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1298         started = cur_ops->get_gp_seq();
1299         ts = rcu_trace_clock_local();
1300         p = rcu_dereference_check(rcu_torture_current,
1301                                   rcu_read_lock_bh_held() ||
1302                                   rcu_read_lock_sched_held() ||
1303                                   srcu_read_lock_held(srcu_ctlp) ||
1304                                   torturing_tasks());
1305         if (p == NULL) {
1306                 /* Wait for rcu_torture_writer to get underway */
1307                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1308                 return false;
1309         }
1310         if (p->rtort_mbtest == 0)
1311                 atomic_inc(&n_rcu_torture_mberror);
1312         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1313         preempt_disable();
1314         pipe_count = p->rtort_pipe_count;
1315         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1316                 /* Should not happen, but... */
1317                 pipe_count = RCU_TORTURE_PIPE_LEN;
1318         }
1319         completed = cur_ops->get_gp_seq();
1320         if (pipe_count > 1) {
1321                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1322                                           ts, started, completed);
1323                 rcu_ftrace_dump(DUMP_ALL);
1324         }
1325         __this_cpu_inc(rcu_torture_count[pipe_count]);
1326         completed = rcutorture_seq_diff(completed, started);
1327         if (completed > RCU_TORTURE_PIPE_LEN) {
1328                 /* Should not happen, but... */
1329                 completed = RCU_TORTURE_PIPE_LEN;
1330         }
1331         __this_cpu_inc(rcu_torture_batch[completed]);
1332         preempt_enable();
1333         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1334         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1335
1336         /* If error or close call, record the sequence of reader protections. */
1337         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1338                 i = 0;
1339                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1340                         err_segs[i++] = *rtrsp1;
1341                 rt_read_nsegs = i;
1342         }
1343
1344         return true;
1345 }
1346
1347 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1348
1349 /*
1350  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1351  * incrementing the corresponding element of the pipeline array.  The
1352  * counter in the element should never be greater than 1, otherwise, the
1353  * RCU implementation is broken.
1354  */
1355 static void rcu_torture_timer(struct timer_list *unused)
1356 {
1357         atomic_long_inc(&n_rcu_torture_timers);
1358         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1359
1360         /* Test call_rcu() invocation from interrupt handler. */
1361         if (cur_ops->call) {
1362                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1363
1364                 if (rhp)
1365                         cur_ops->call(rhp, rcu_torture_timer_cb);
1366         }
1367 }
1368
1369 /*
1370  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1371  * incrementing the corresponding element of the pipeline array.  The
1372  * counter in the element should never be greater than 1, otherwise, the
1373  * RCU implementation is broken.
1374  */
1375 static int
1376 rcu_torture_reader(void *arg)
1377 {
1378         unsigned long lastsleep = jiffies;
1379         long myid = (long)arg;
1380         int mynumonline = myid;
1381         DEFINE_TORTURE_RANDOM(rand);
1382         struct timer_list t;
1383
1384         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1385         set_user_nice(current, MAX_NICE);
1386         if (irqreader && cur_ops->irq_capable)
1387                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1388
1389         do {
1390                 if (irqreader && cur_ops->irq_capable) {
1391                         if (!timer_pending(&t))
1392                                 mod_timer(&t, jiffies + 1);
1393                 }
1394                 if (!rcu_torture_one_read(&rand))
1395                         schedule_timeout_interruptible(HZ);
1396                 if (time_after(jiffies, lastsleep)) {
1397                         schedule_timeout_interruptible(1);
1398                         lastsleep = jiffies + 10;
1399                 }
1400                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1401                         schedule_timeout_interruptible(HZ / 5);
1402                 stutter_wait("rcu_torture_reader");
1403         } while (!torture_must_stop());
1404         if (irqreader && cur_ops->irq_capable) {
1405                 del_timer_sync(&t);
1406                 destroy_timer_on_stack(&t);
1407         }
1408         torture_kthread_stopping("rcu_torture_reader");
1409         return 0;
1410 }
1411
1412 /*
1413  * Print torture statistics.  Caller must ensure that there is only
1414  * one call to this function at a given time!!!  This is normally
1415  * accomplished by relying on the module system to only have one copy
1416  * of the module loaded, and then by giving the rcu_torture_stats
1417  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1418  * thread is not running).
1419  */
1420 static void
1421 rcu_torture_stats_print(void)
1422 {
1423         int cpu;
1424         int i;
1425         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1426         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1427         static unsigned long rtcv_snap = ULONG_MAX;
1428         static bool splatted;
1429         struct task_struct *wtp;
1430
1431         for_each_possible_cpu(cpu) {
1432                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1433                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1434                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1435                 }
1436         }
1437         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1438                 if (pipesummary[i] != 0)
1439                         break;
1440         }
1441
1442         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1443         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1444                 rcu_torture_current,
1445                 rcu_torture_current_version,
1446                 list_empty(&rcu_torture_freelist),
1447                 atomic_read(&n_rcu_torture_alloc),
1448                 atomic_read(&n_rcu_torture_alloc_fail),
1449                 atomic_read(&n_rcu_torture_free));
1450         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1451                 atomic_read(&n_rcu_torture_mberror),
1452                 n_rcu_torture_barrier_error,
1453                 n_rcu_torture_boost_ktrerror,
1454                 n_rcu_torture_boost_rterror);
1455         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1456                 n_rcu_torture_boost_failure,
1457                 n_rcu_torture_boosts,
1458                 atomic_long_read(&n_rcu_torture_timers));
1459         torture_onoff_stats();
1460         pr_cont("barrier: %ld/%ld:%ld ",
1461                 n_barrier_successes,
1462                 n_barrier_attempts,
1463                 n_rcu_torture_barrier_error);
1464         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1465
1466         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1467         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1468             n_rcu_torture_barrier_error != 0 ||
1469             n_rcu_torture_boost_ktrerror != 0 ||
1470             n_rcu_torture_boost_rterror != 0 ||
1471             n_rcu_torture_boost_failure != 0 ||
1472             i > 1) {
1473                 pr_cont("%s", "!!! ");
1474                 atomic_inc(&n_rcu_torture_error);
1475                 WARN_ON_ONCE(1);
1476         }
1477         pr_cont("Reader Pipe: ");
1478         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1479                 pr_cont(" %ld", pipesummary[i]);
1480         pr_cont("\n");
1481
1482         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1483         pr_cont("Reader Batch: ");
1484         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1485                 pr_cont(" %ld", batchsummary[i]);
1486         pr_cont("\n");
1487
1488         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1489         pr_cont("Free-Block Circulation: ");
1490         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1491                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1492         }
1493         pr_cont("\n");
1494
1495         if (cur_ops->stats)
1496                 cur_ops->stats();
1497         if (rtcv_snap == rcu_torture_current_version &&
1498             rcu_torture_current != NULL) {
1499                 int __maybe_unused flags = 0;
1500                 unsigned long __maybe_unused gp_seq = 0;
1501
1502                 rcutorture_get_gp_data(cur_ops->ttype,
1503                                        &flags, &gp_seq);
1504                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1505                                         &flags, &gp_seq);
1506                 wtp = READ_ONCE(writer_task);
1507                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1508                          rcu_torture_writer_state_getname(),
1509                          rcu_torture_writer_state, gp_seq, flags,
1510                          wtp == NULL ? ~0UL : wtp->state,
1511                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1512                 if (!splatted && wtp) {
1513                         sched_show_task(wtp);
1514                         splatted = true;
1515                 }
1516                 show_rcu_gp_kthreads();
1517                 rcu_ftrace_dump(DUMP_ALL);
1518         }
1519         rtcv_snap = rcu_torture_current_version;
1520 }
1521
1522 /*
1523  * Periodically prints torture statistics, if periodic statistics printing
1524  * was specified via the stat_interval module parameter.
1525  */
1526 static int
1527 rcu_torture_stats(void *arg)
1528 {
1529         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1530         do {
1531                 schedule_timeout_interruptible(stat_interval * HZ);
1532                 rcu_torture_stats_print();
1533                 torture_shutdown_absorb("rcu_torture_stats");
1534         } while (!torture_must_stop());
1535         torture_kthread_stopping("rcu_torture_stats");
1536         return 0;
1537 }
1538
1539 static void
1540 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1541 {
1542         pr_alert("%s" TORTURE_FLAG
1543                  "--- %s: nreaders=%d nfakewriters=%d "
1544                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1545                  "shuffle_interval=%d stutter=%d irqreader=%d "
1546                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1547                  "test_boost=%d/%d test_boost_interval=%d "
1548                  "test_boost_duration=%d shutdown_secs=%d "
1549                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1550                  "n_barrier_cbs=%d "
1551                  "onoff_interval=%d onoff_holdoff=%d\n",
1552                  torture_type, tag, nrealreaders, nfakewriters,
1553                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1554                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1555                  test_boost, cur_ops->can_boost,
1556                  test_boost_interval, test_boost_duration, shutdown_secs,
1557                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1558                  n_barrier_cbs,
1559                  onoff_interval, onoff_holdoff);
1560 }
1561
1562 static int rcutorture_booster_cleanup(unsigned int cpu)
1563 {
1564         struct task_struct *t;
1565
1566         if (boost_tasks[cpu] == NULL)
1567                 return 0;
1568         mutex_lock(&boost_mutex);
1569         t = boost_tasks[cpu];
1570         boost_tasks[cpu] = NULL;
1571         rcu_torture_enable_rt_throttle();
1572         mutex_unlock(&boost_mutex);
1573
1574         /* This must be outside of the mutex, otherwise deadlock! */
1575         torture_stop_kthread(rcu_torture_boost, t);
1576         return 0;
1577 }
1578
1579 static int rcutorture_booster_init(unsigned int cpu)
1580 {
1581         int retval;
1582
1583         if (boost_tasks[cpu] != NULL)
1584                 return 0;  /* Already created, nothing more to do. */
1585
1586         /* Don't allow time recalculation while creating a new task. */
1587         mutex_lock(&boost_mutex);
1588         rcu_torture_disable_rt_throttle();
1589         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1590         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1591                                                   cpu_to_node(cpu),
1592                                                   "rcu_torture_boost");
1593         if (IS_ERR(boost_tasks[cpu])) {
1594                 retval = PTR_ERR(boost_tasks[cpu]);
1595                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1596                 n_rcu_torture_boost_ktrerror++;
1597                 boost_tasks[cpu] = NULL;
1598                 mutex_unlock(&boost_mutex);
1599                 return retval;
1600         }
1601         kthread_bind(boost_tasks[cpu], cpu);
1602         wake_up_process(boost_tasks[cpu]);
1603         mutex_unlock(&boost_mutex);
1604         return 0;
1605 }
1606
1607 /*
1608  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1609  * induces a CPU stall for the time specified by stall_cpu.
1610  */
1611 static int rcu_torture_stall(void *args)
1612 {
1613         unsigned long stop_at;
1614
1615         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1616         if (stall_cpu_holdoff > 0) {
1617                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1618                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1619                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1620         }
1621         if (!kthread_should_stop()) {
1622                 stop_at = ktime_get_seconds() + stall_cpu;
1623                 /* RCU CPU stall is expected behavior in following code. */
1624                 rcu_read_lock();
1625                 if (stall_cpu_irqsoff)
1626                         local_irq_disable();
1627                 else
1628                         preempt_disable();
1629                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1630                          smp_processor_id());
1631                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1632                                     stop_at))
1633                         continue;  /* Induce RCU CPU stall warning. */
1634                 if (stall_cpu_irqsoff)
1635                         local_irq_enable();
1636                 else
1637                         preempt_enable();
1638                 rcu_read_unlock();
1639                 pr_alert("rcu_torture_stall end.\n");
1640         }
1641         torture_shutdown_absorb("rcu_torture_stall");
1642         while (!kthread_should_stop())
1643                 schedule_timeout_interruptible(10 * HZ);
1644         return 0;
1645 }
1646
1647 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1648 static int __init rcu_torture_stall_init(void)
1649 {
1650         if (stall_cpu <= 0)
1651                 return 0;
1652         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1653 }
1654
1655 /* State structure for forward-progress self-propagating RCU callback. */
1656 struct fwd_cb_state {
1657         struct rcu_head rh;
1658         int stop;
1659 };
1660
1661 /*
1662  * Forward-progress self-propagating RCU callback function.  Because
1663  * callbacks run from softirq, this function is an implicit RCU read-side
1664  * critical section.
1665  */
1666 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1667 {
1668         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1669
1670         if (READ_ONCE(fcsp->stop)) {
1671                 WRITE_ONCE(fcsp->stop, 2);
1672                 return;
1673         }
1674         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1675 }
1676
1677 /* Carry out grace-period forward-progress testing. */
1678 static int rcu_torture_fwd_prog(void *args)
1679 {
1680         unsigned long cver;
1681         unsigned long dur;
1682         struct fwd_cb_state fcs;
1683         unsigned long gps;
1684         int idx;
1685         int sd;
1686         int sd4;
1687         bool selfpropcb = false;
1688         unsigned long stopat;
1689         int tested = 0;
1690         int tested_tries = 0;
1691         static DEFINE_TORTURE_RANDOM(trs);
1692
1693         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1694         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1695                 set_user_nice(current, MAX_NICE);
1696         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1697                 init_rcu_head_on_stack(&fcs.rh);
1698                 selfpropcb = true;
1699         }
1700         do {
1701                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1702                 if  (selfpropcb) {
1703                         WRITE_ONCE(fcs.stop, 0);
1704                         cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1705                 }
1706                 cver = READ_ONCE(rcu_torture_current_version);
1707                 gps = cur_ops->get_gp_seq();
1708                 sd = cur_ops->stall_dur() + 1;
1709                 sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1710                 dur = sd4 + torture_random(&trs) % (sd - sd4);
1711                 stopat = jiffies + dur;
1712                 while (time_before(jiffies, stopat) && !torture_must_stop()) {
1713                         idx = cur_ops->readlock();
1714                         udelay(10);
1715                         cur_ops->readunlock(idx);
1716                         if (!fwd_progress_need_resched || need_resched())
1717                                 cond_resched();
1718                 }
1719                 tested_tries++;
1720                 if (!time_before(jiffies, stopat) && !torture_must_stop()) {
1721                         tested++;
1722                         cver = READ_ONCE(rcu_torture_current_version) - cver;
1723                         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1724                         WARN_ON(!cver && gps < 2);
1725                         pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1726                 }
1727                 if (selfpropcb) {
1728                         WRITE_ONCE(fcs.stop, 1);
1729                         cur_ops->sync(); /* Wait for running CB to complete. */
1730                         cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1731                 }
1732                 /* Avoid slow periods, better to test when busy. */
1733                 stutter_wait("rcu_torture_fwd_prog");
1734         } while (!torture_must_stop());
1735         if (selfpropcb) {
1736                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1737                 destroy_rcu_head_on_stack(&fcs.rh);
1738         }
1739         /* Short runs might not contain a valid forward-progress attempt. */
1740         WARN_ON(!tested && tested_tries >= 5);
1741         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1742         torture_kthread_stopping("rcu_torture_fwd_prog");
1743         return 0;
1744 }
1745
1746 /* If forward-progress checking is requested and feasible, spawn the thread. */
1747 static int __init rcu_torture_fwd_prog_init(void)
1748 {
1749         if (!fwd_progress)
1750                 return 0; /* Not requested, so don't do it. */
1751         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0) {
1752                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1753                 return 0;
1754         }
1755         if (stall_cpu > 0) {
1756                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1757                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1758                         return -EINVAL; /* In module, can fail back to user. */
1759                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1760                 return 0;
1761         }
1762         if (fwd_progress_holdoff <= 0)
1763                 fwd_progress_holdoff = 1;
1764         if (fwd_progress_div <= 0)
1765                 fwd_progress_div = 4;
1766         return torture_create_kthread(rcu_torture_fwd_prog,
1767                                       NULL, fwd_prog_task);
1768 }
1769
1770 /* Callback function for RCU barrier testing. */
1771 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1772 {
1773         atomic_inc(&barrier_cbs_invoked);
1774 }
1775
1776 /* kthread function to register callbacks used to test RCU barriers. */
1777 static int rcu_torture_barrier_cbs(void *arg)
1778 {
1779         long myid = (long)arg;
1780         bool lastphase = 0;
1781         bool newphase;
1782         struct rcu_head rcu;
1783
1784         init_rcu_head_on_stack(&rcu);
1785         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1786         set_user_nice(current, MAX_NICE);
1787         do {
1788                 wait_event(barrier_cbs_wq[myid],
1789                            (newphase =
1790                             smp_load_acquire(&barrier_phase)) != lastphase ||
1791                            torture_must_stop());
1792                 lastphase = newphase;
1793                 if (torture_must_stop())
1794                         break;
1795                 /*
1796                  * The above smp_load_acquire() ensures barrier_phase load
1797                  * is ordered before the following ->call().
1798                  */
1799                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1800                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1801                 local_irq_enable();
1802                 if (atomic_dec_and_test(&barrier_cbs_count))
1803                         wake_up(&barrier_wq);
1804         } while (!torture_must_stop());
1805         if (cur_ops->cb_barrier != NULL)
1806                 cur_ops->cb_barrier();
1807         destroy_rcu_head_on_stack(&rcu);
1808         torture_kthread_stopping("rcu_torture_barrier_cbs");
1809         return 0;
1810 }
1811
1812 /* kthread function to drive and coordinate RCU barrier testing. */
1813 static int rcu_torture_barrier(void *arg)
1814 {
1815         int i;
1816
1817         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1818         do {
1819                 atomic_set(&barrier_cbs_invoked, 0);
1820                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1821                 /* Ensure barrier_phase ordered after prior assignments. */
1822                 smp_store_release(&barrier_phase, !barrier_phase);
1823                 for (i = 0; i < n_barrier_cbs; i++)
1824                         wake_up(&barrier_cbs_wq[i]);
1825                 wait_event(barrier_wq,
1826                            atomic_read(&barrier_cbs_count) == 0 ||
1827                            torture_must_stop());
1828                 if (torture_must_stop())
1829                         break;
1830                 n_barrier_attempts++;
1831                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1832                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1833                         n_rcu_torture_barrier_error++;
1834                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1835                                atomic_read(&barrier_cbs_invoked),
1836                                n_barrier_cbs);
1837                         WARN_ON_ONCE(1);
1838                 } else {
1839                         n_barrier_successes++;
1840                 }
1841                 schedule_timeout_interruptible(HZ / 10);
1842         } while (!torture_must_stop());
1843         torture_kthread_stopping("rcu_torture_barrier");
1844         return 0;
1845 }
1846
1847 /* Initialize RCU barrier testing. */
1848 static int rcu_torture_barrier_init(void)
1849 {
1850         int i;
1851         int ret;
1852
1853         if (n_barrier_cbs <= 0)
1854                 return 0;
1855         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1856                 pr_alert("%s" TORTURE_FLAG
1857                          " Call or barrier ops missing for %s,\n",
1858                          torture_type, cur_ops->name);
1859                 pr_alert("%s" TORTURE_FLAG
1860                          " RCU barrier testing omitted from run.\n",
1861                          torture_type);
1862                 return 0;
1863         }
1864         atomic_set(&barrier_cbs_count, 0);
1865         atomic_set(&barrier_cbs_invoked, 0);
1866         barrier_cbs_tasks =
1867                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
1868                         GFP_KERNEL);
1869         barrier_cbs_wq =
1870                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
1871         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1872                 return -ENOMEM;
1873         for (i = 0; i < n_barrier_cbs; i++) {
1874                 init_waitqueue_head(&barrier_cbs_wq[i]);
1875                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1876                                              (void *)(long)i,
1877                                              barrier_cbs_tasks[i]);
1878                 if (ret)
1879                         return ret;
1880         }
1881         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1882 }
1883
1884 /* Clean up after RCU barrier testing. */
1885 static void rcu_torture_barrier_cleanup(void)
1886 {
1887         int i;
1888
1889         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1890         if (barrier_cbs_tasks != NULL) {
1891                 for (i = 0; i < n_barrier_cbs; i++)
1892                         torture_stop_kthread(rcu_torture_barrier_cbs,
1893                                              barrier_cbs_tasks[i]);
1894                 kfree(barrier_cbs_tasks);
1895                 barrier_cbs_tasks = NULL;
1896         }
1897         if (barrier_cbs_wq != NULL) {
1898                 kfree(barrier_cbs_wq);
1899                 barrier_cbs_wq = NULL;
1900         }
1901 }
1902
1903 static bool rcu_torture_can_boost(void)
1904 {
1905         static int boost_warn_once;
1906         int prio;
1907
1908         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
1909                 return false;
1910
1911         prio = rcu_get_gp_kthreads_prio();
1912         if (!prio)
1913                 return false;
1914
1915         if (prio < 2) {
1916                 if (boost_warn_once  == 1)
1917                         return false;
1918
1919                 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);
1920                 boost_warn_once = 1;
1921                 return false;
1922         }
1923
1924         return true;
1925 }
1926
1927 static enum cpuhp_state rcutor_hp;
1928
1929 static void
1930 rcu_torture_cleanup(void)
1931 {
1932         int firsttime;
1933         int flags = 0;
1934         unsigned long gp_seq = 0;
1935         int i;
1936
1937         if (torture_cleanup_begin()) {
1938                 if (cur_ops->cb_barrier != NULL)
1939                         cur_ops->cb_barrier();
1940                 return;
1941         }
1942
1943         rcu_torture_barrier_cleanup();
1944         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
1945         torture_stop_kthread(rcu_torture_stall, stall_task);
1946         torture_stop_kthread(rcu_torture_writer, writer_task);
1947
1948         if (reader_tasks) {
1949                 for (i = 0; i < nrealreaders; i++)
1950                         torture_stop_kthread(rcu_torture_reader,
1951                                              reader_tasks[i]);
1952                 kfree(reader_tasks);
1953         }
1954         rcu_torture_current = NULL;
1955
1956         if (fakewriter_tasks) {
1957                 for (i = 0; i < nfakewriters; i++) {
1958                         torture_stop_kthread(rcu_torture_fakewriter,
1959                                              fakewriter_tasks[i]);
1960                 }
1961                 kfree(fakewriter_tasks);
1962                 fakewriter_tasks = NULL;
1963         }
1964
1965         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
1966         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
1967         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
1968                  cur_ops->name, gp_seq, flags);
1969         torture_stop_kthread(rcu_torture_stats, stats_task);
1970         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1971         for (i = 0; i < ncbflooders; i++)
1972                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1973         if (rcu_torture_can_boost())
1974                 cpuhp_remove_state(rcutor_hp);
1975
1976         /*
1977          * Wait for all RCU callbacks to fire, then do torture-type-specific
1978          * cleanup operations.
1979          */
1980         if (cur_ops->cb_barrier != NULL)
1981                 cur_ops->cb_barrier();
1982         if (cur_ops->cleanup != NULL)
1983                 cur_ops->cleanup();
1984
1985         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1986
1987         if (err_segs_recorded) {
1988                 pr_alert("Failure/close-call rcutorture reader segments:\n");
1989                 if (rt_read_nsegs == 0)
1990                         pr_alert("\t: No segments recorded!!!\n");
1991                 firsttime = 1;
1992                 for (i = 0; i < rt_read_nsegs; i++) {
1993                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
1994                         if (err_segs[i].rt_delay_jiffies != 0) {
1995                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
1996                                         err_segs[i].rt_delay_jiffies);
1997                                 firsttime = 0;
1998                         }
1999                         if (err_segs[i].rt_delay_ms != 0) {
2000                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2001                                         err_segs[i].rt_delay_ms);
2002                                 firsttime = 0;
2003                         }
2004                         if (err_segs[i].rt_delay_us != 0) {
2005                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2006                                         err_segs[i].rt_delay_us);
2007                                 firsttime = 0;
2008                         }
2009                         pr_cont("%s\n",
2010                                 err_segs[i].rt_preempted ? "preempted" : "");
2011
2012                 }
2013         }
2014         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2015                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2016         else if (torture_onoff_failures())
2017                 rcu_torture_print_module_parms(cur_ops,
2018                                                "End of test: RCU_HOTPLUG");
2019         else
2020                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2021         torture_cleanup_end();
2022 }
2023
2024 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2025 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2026 {
2027 }
2028
2029 static void rcu_torture_err_cb(struct rcu_head *rhp)
2030 {
2031         /*
2032          * This -might- happen due to race conditions, but is unlikely.
2033          * The scenario that leads to this happening is that the
2034          * first of the pair of duplicate callbacks is queued,
2035          * someone else starts a grace period that includes that
2036          * callback, then the second of the pair must wait for the
2037          * next grace period.  Unlikely, but can happen.  If it
2038          * does happen, the debug-objects subsystem won't have splatted.
2039          */
2040         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2041 }
2042 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2043
2044 /*
2045  * Verify that double-free causes debug-objects to complain, but only
2046  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2047  * cannot be carried out.
2048  */
2049 static void rcu_test_debug_objects(void)
2050 {
2051 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2052         struct rcu_head rh1;
2053         struct rcu_head rh2;
2054
2055         init_rcu_head_on_stack(&rh1);
2056         init_rcu_head_on_stack(&rh2);
2057         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2058
2059         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2060         preempt_disable(); /* Prevent preemption from interrupting test. */
2061         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2062         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2063         local_irq_disable(); /* Make it harder to start a new grace period. */
2064         call_rcu(&rh2, rcu_torture_leak_cb);
2065         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2066         local_irq_enable();
2067         rcu_read_unlock();
2068         preempt_enable();
2069
2070         /* Wait for them all to get done so we can safely return. */
2071         rcu_barrier();
2072         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2073         destroy_rcu_head_on_stack(&rh1);
2074         destroy_rcu_head_on_stack(&rh2);
2075 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2076         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2077 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2078 }
2079
2080 static int __init
2081 rcu_torture_init(void)
2082 {
2083         long i;
2084         int cpu;
2085         int firsterr = 0;
2086         static struct rcu_torture_ops *torture_ops[] = {
2087                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2088                 &busted_srcud_ops, &tasks_ops,
2089         };
2090
2091         if (!torture_init_begin(torture_type, verbose))
2092                 return -EBUSY;
2093
2094         /* Process args and tell the world that the torturer is on the job. */
2095         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2096                 cur_ops = torture_ops[i];
2097                 if (strcmp(torture_type, cur_ops->name) == 0)
2098                         break;
2099         }
2100         if (i == ARRAY_SIZE(torture_ops)) {
2101                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2102                          torture_type);
2103                 pr_alert("rcu-torture types:");
2104                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2105                         pr_cont(" %s", torture_ops[i]->name);
2106                 pr_cont("\n");
2107                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2108                 firsterr = -EINVAL;
2109                 goto unwind;
2110         }
2111         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2112                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2113                 fqs_duration = 0;
2114         }
2115         if (cur_ops->init)
2116                 cur_ops->init();
2117
2118         if (nreaders >= 0) {
2119                 nrealreaders = nreaders;
2120         } else {
2121                 nrealreaders = num_online_cpus() - 2 - nreaders;
2122                 if (nrealreaders <= 0)
2123                         nrealreaders = 1;
2124         }
2125         rcu_torture_print_module_parms(cur_ops, "Start of test");
2126
2127         /* Set up the freelist. */
2128
2129         INIT_LIST_HEAD(&rcu_torture_freelist);
2130         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2131                 rcu_tortures[i].rtort_mbtest = 0;
2132                 list_add_tail(&rcu_tortures[i].rtort_free,
2133                               &rcu_torture_freelist);
2134         }
2135
2136         /* Initialize the statistics so that each run gets its own numbers. */
2137
2138         rcu_torture_current = NULL;
2139         rcu_torture_current_version = 0;
2140         atomic_set(&n_rcu_torture_alloc, 0);
2141         atomic_set(&n_rcu_torture_alloc_fail, 0);
2142         atomic_set(&n_rcu_torture_free, 0);
2143         atomic_set(&n_rcu_torture_mberror, 0);
2144         atomic_set(&n_rcu_torture_error, 0);
2145         n_rcu_torture_barrier_error = 0;
2146         n_rcu_torture_boost_ktrerror = 0;
2147         n_rcu_torture_boost_rterror = 0;
2148         n_rcu_torture_boost_failure = 0;
2149         n_rcu_torture_boosts = 0;
2150         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2151                 atomic_set(&rcu_torture_wcount[i], 0);
2152         for_each_possible_cpu(cpu) {
2153                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2154                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2155                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2156                 }
2157         }
2158         err_segs_recorded = 0;
2159         rt_read_nsegs = 0;
2160
2161         /* Start up the kthreads. */
2162
2163         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2164                                           writer_task);
2165         if (firsterr)
2166                 goto unwind;
2167         if (nfakewriters > 0) {
2168                 fakewriter_tasks = kcalloc(nfakewriters,
2169                                            sizeof(fakewriter_tasks[0]),
2170                                            GFP_KERNEL);
2171                 if (fakewriter_tasks == NULL) {
2172                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2173                         firsterr = -ENOMEM;
2174                         goto unwind;
2175                 }
2176         }
2177         for (i = 0; i < nfakewriters; i++) {
2178                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2179                                                   NULL, fakewriter_tasks[i]);
2180                 if (firsterr)
2181                         goto unwind;
2182         }
2183         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2184                                GFP_KERNEL);
2185         if (reader_tasks == NULL) {
2186                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2187                 firsterr = -ENOMEM;
2188                 goto unwind;
2189         }
2190         for (i = 0; i < nrealreaders; i++) {
2191                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2192                                                   reader_tasks[i]);
2193                 if (firsterr)
2194                         goto unwind;
2195         }
2196         if (stat_interval > 0) {
2197                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2198                                                   stats_task);
2199                 if (firsterr)
2200                         goto unwind;
2201         }
2202         if (test_no_idle_hz && shuffle_interval > 0) {
2203                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2204                 if (firsterr)
2205                         goto unwind;
2206         }
2207         if (stutter < 0)
2208                 stutter = 0;
2209         if (stutter) {
2210                 firsterr = torture_stutter_init(stutter * HZ);
2211                 if (firsterr)
2212                         goto unwind;
2213         }
2214         if (fqs_duration < 0)
2215                 fqs_duration = 0;
2216         if (fqs_duration) {
2217                 /* Create the fqs thread */
2218                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2219                                                   fqs_task);
2220                 if (firsterr)
2221                         goto unwind;
2222         }
2223         if (test_boost_interval < 1)
2224                 test_boost_interval = 1;
2225         if (test_boost_duration < 2)
2226                 test_boost_duration = 2;
2227         if (rcu_torture_can_boost()) {
2228
2229                 boost_starttime = jiffies + test_boost_interval * HZ;
2230
2231                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2232                                              rcutorture_booster_init,
2233                                              rcutorture_booster_cleanup);
2234                 if (firsterr < 0)
2235                         goto unwind;
2236                 rcutor_hp = firsterr;
2237         }
2238         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2239         if (firsterr)
2240                 goto unwind;
2241         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
2242         if (firsterr)
2243                 goto unwind;
2244         firsterr = rcu_torture_stall_init();
2245         if (firsterr)
2246                 goto unwind;
2247         firsterr = rcu_torture_fwd_prog_init();
2248         if (firsterr)
2249                 goto unwind;
2250         firsterr = rcu_torture_barrier_init();
2251         if (firsterr)
2252                 goto unwind;
2253         if (object_debug)
2254                 rcu_test_debug_objects();
2255         if (cbflood_n_burst > 0) {
2256                 /* Create the cbflood threads */
2257                 ncbflooders = (num_online_cpus() + 3) / 4;
2258                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
2259                                        GFP_KERNEL);
2260                 if (!cbflood_task) {
2261                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2262                         firsterr = -ENOMEM;
2263                         goto unwind;
2264                 }
2265                 for (i = 0; i < ncbflooders; i++) {
2266                         firsterr = torture_create_kthread(rcu_torture_cbflood,
2267                                                           NULL,
2268                                                           cbflood_task[i]);
2269                         if (firsterr)
2270                                 goto unwind;
2271                 }
2272         }
2273         torture_init_end();
2274         return 0;
2275
2276 unwind:
2277         torture_init_end();
2278         rcu_torture_cleanup();
2279         return firsterr;
2280 }
2281
2282 module_init(rcu_torture_init);
2283 module_exit(rcu_torture_cleanup);