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 <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@joshtriplett.org>
  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 #include <linux/oom.h>
  60
  61 #include "rcu.h"
  62
  63 MODULE_LICENSE("GPL");
  64 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  65
  66
  67 /* Bits for ->extendables field, extendables param, and related definitions. */
  68 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  69 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  70 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  71 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  72 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  73 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  74 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  75 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  76 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  77 #define RCUTORTURE_MAX_EXTEND    \
  78         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  79          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  80 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  81                                         /* Must be power of two minus one. */
  82 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  83
  84 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  85               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  86 torture_param(int, fqs_duration, 0,
  87               "Duration of fqs bursts (us), 0 to disable");
  88 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  89 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  90 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  91 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  92 torture_param(int, fwd_progress_holdoff, 60,
  93               "Time between forward-progress tests (s)");
  94 torture_param(bool, fwd_progress_need_resched, 1,
  95               "Hide cond_resched() behind need_resched()");
  96 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  97 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  98 torture_param(bool, gp_normal, false,
  99              "Use normal (non-expedited) GP wait primitives");
 100 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
 101 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
 102 torture_param(int, n_barrier_cbs, 0,
 103              "# of callbacks/kthreads for barrier testing");
 104 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
 105 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 106 torture_param(int, object_debug, 0,
 107              "Enable debug-object double call_rcu() testing");
 108 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
 109 torture_param(int, onoff_interval, 0,
 110              "Time between CPU hotplugs (jiffies), 0=disable");
 111 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 112 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 113 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 114 torture_param(int, stall_cpu_holdoff, 10,
 115              "Time to wait before starting stall (s).");
 116 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 117 torture_param(int, stat_interval, 60,
 118              "Number of seconds between stats printk()s");
 119 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 120 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 121 torture_param(int, test_boost_duration, 4,
 122              "Duration of each boost test, seconds.");
 123 torture_param(int, test_boost_interval, 7,
 124              "Interval between boost tests, seconds.");
 125 torture_param(bool, test_no_idle_hz, true,
 126              "Test support for tickless idle CPUs");
 127 torture_param(int, verbose, 1,
 128              "Enable verbose debugging printk()s");
 129
 130 static char *torture_type = "rcu";
 131 module_param(torture_type, charp, 0444);
 132 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 133
 134 static int nrealreaders;
 135 static struct task_struct *writer_task;
 136 static struct task_struct **fakewriter_tasks;
 137 static struct task_struct **reader_tasks;
 138 static struct task_struct *stats_task;
 139 static struct task_struct *fqs_task;
 140 static struct task_struct *boost_tasks[NR_CPUS];
 141 static struct task_struct *stall_task;
 142 static struct task_struct *fwd_prog_task;
 143 static struct task_struct **barrier_cbs_tasks;
 144 static struct task_struct *barrier_task;
 145
 146 #define RCU_TORTURE_PIPE_LEN 10
 147
 148 struct rcu_torture {
 149         struct rcu_head rtort_rcu;
 150         int rtort_pipe_count;
 151         struct list_head rtort_free;
 152         int rtort_mbtest;
 153 };
 154
 155 static LIST_HEAD(rcu_torture_freelist);
 156 static struct rcu_torture __rcu *rcu_torture_current;
 157 static unsigned long rcu_torture_current_version;
 158 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 159 static DEFINE_SPINLOCK(rcu_torture_lock);
 160 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 161 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 162 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 163 static atomic_t n_rcu_torture_alloc;
 164 static atomic_t n_rcu_torture_alloc_fail;
 165 static atomic_t n_rcu_torture_free;
 166 static atomic_t n_rcu_torture_mberror;
 167 static atomic_t n_rcu_torture_error;
 168 static long n_rcu_torture_barrier_error;
 169 static long n_rcu_torture_boost_ktrerror;
 170 static long n_rcu_torture_boost_rterror;
 171 static long n_rcu_torture_boost_failure;
 172 static long n_rcu_torture_boosts;
 173 static atomic_long_t n_rcu_torture_timers;
 174 static long n_barrier_attempts;
 175 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 176 static struct list_head rcu_torture_removed;
 177
 178 static int rcu_torture_writer_state;
 179 #define RTWS_FIXED_DELAY        0
 180 #define RTWS_DELAY              1
 181 #define RTWS_REPLACE            2
 182 #define RTWS_DEF_FREE           3
 183 #define RTWS_EXP_SYNC           4
 184 #define RTWS_COND_GET           5
 185 #define RTWS_COND_SYNC          6
 186 #define RTWS_SYNC               7
 187 #define RTWS_STUTTER            8
 188 #define RTWS_STOPPING           9
 189 static const char * const rcu_torture_writer_state_names[] = {
 190         "RTWS_FIXED_DELAY",
 191         "RTWS_DELAY",
 192         "RTWS_REPLACE",
 193         "RTWS_DEF_FREE",
 194         "RTWS_EXP_SYNC",
 195         "RTWS_COND_GET",
 196         "RTWS_COND_SYNC",
 197         "RTWS_SYNC",
 198         "RTWS_STUTTER",
 199         "RTWS_STOPPING",
 200 };
 201
 202 /* Record reader segment types and duration for first failing read. */
 203 struct rt_read_seg {
 204         int rt_readstate;
 205         unsigned long rt_delay_jiffies;
 206         unsigned long rt_delay_ms;
 207         unsigned long rt_delay_us;
 208         bool rt_preempted;
 209 };
 210 static int err_segs_recorded;
 211 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 212 static int rt_read_nsegs;
 213
 214 static const char *rcu_torture_writer_state_getname(void)
 215 {
 216         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 217
 218         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 219                 return "???";
 220         return rcu_torture_writer_state_names[i];
 221 }
 222
 223 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 224 #define rcu_can_boost() 1
 225 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 226 #define rcu_can_boost() 0
 227 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 228
 229 #ifdef CONFIG_RCU_TRACE
 230 static u64 notrace rcu_trace_clock_local(void)
 231 {
 232         u64 ts = trace_clock_local();
 233
 234         (void)do_div(ts, NSEC_PER_USEC);
 235         return ts;
 236 }
 237 #else /* #ifdef CONFIG_RCU_TRACE */
 238 static u64 notrace rcu_trace_clock_local(void)
 239 {
 240         return 0ULL;
 241 }
 242 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 243
 244 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 245 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 246                                         /*  and boost task create/destroy. */
 247 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 248 static bool barrier_phase;              /* Test phase. */
 249 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 250 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 251 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 252
 253 static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 254
 255 /*
 256  * Allocate an element from the rcu_tortures pool.
 257  */
 258 static struct rcu_torture *
 259 rcu_torture_alloc(void)
 260 {
 261         struct list_head *p;
 262
 263         spin_lock_bh(&rcu_torture_lock);
 264         if (list_empty(&rcu_torture_freelist)) {
 265                 atomic_inc(&n_rcu_torture_alloc_fail);
 266                 spin_unlock_bh(&rcu_torture_lock);
 267                 return NULL;
 268         }
 269         atomic_inc(&n_rcu_torture_alloc);
 270         p = rcu_torture_freelist.next;
 271         list_del_init(p);
 272         spin_unlock_bh(&rcu_torture_lock);
 273         return container_of(p, struct rcu_torture, rtort_free);
 274 }
 275
 276 /*
 277  * Free an element to the rcu_tortures pool.
 278  */
 279 static void
 280 rcu_torture_free(struct rcu_torture *p)
 281 {
 282         atomic_inc(&n_rcu_torture_free);
 283         spin_lock_bh(&rcu_torture_lock);
 284         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 285         spin_unlock_bh(&rcu_torture_lock);
 286 }
 287
 288 /*
 289  * Operations vector for selecting different types of tests.
 290  */
 291
 292 struct rcu_torture_ops {
 293         int ttype;
 294         void (*init)(void);
 295         void (*cleanup)(void);
 296         int (*readlock)(void);
 297         void (*read_delay)(struct torture_random_state *rrsp,
 298                            struct rt_read_seg *rtrsp);
 299         void (*readunlock)(int idx);
 300         unsigned long (*get_gp_seq)(void);
 301         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 302         void (*deferred_free)(struct rcu_torture *p);
 303         void (*sync)(void);
 304         void (*exp_sync)(void);
 305         unsigned long (*get_state)(void);
 306         void (*cond_sync)(unsigned long oldstate);
 307         call_rcu_func_t call;
 308         void (*cb_barrier)(void);
 309         void (*fqs)(void);
 310         void (*stats)(void);
 311         int (*stall_dur)(void);
 312         int irq_capable;
 313         int can_boost;
 314         int extendables;
 315         int ext_irq_conflict;
 316         const char *name;
 317 };
 318
 319 static struct rcu_torture_ops *cur_ops;
 320
 321 /*
 322  * Definitions for rcu torture testing.
 323  */
 324
 325 static int rcu_torture_read_lock(void) __acquires(RCU)
 326 {
 327         rcu_read_lock();
 328         return 0;
 329 }
 330
 331 static void
 332 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 333 {
 334         unsigned long started;
 335         unsigned long completed;
 336         const unsigned long shortdelay_us = 200;
 337         unsigned long longdelay_ms = 300;
 338         unsigned long long ts;
 339
 340         /* We want a short delay sometimes to make a reader delay the grace
 341          * period, and we want a long delay occasionally to trigger
 342          * force_quiescent_state. */
 343
 344         if (!rcu_fwd_cb_nodelay &&
 345             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 346                 started = cur_ops->get_gp_seq();
 347                 ts = rcu_trace_clock_local();
 348                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 349                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 350                 mdelay(longdelay_ms);
 351                 rtrsp->rt_delay_ms = longdelay_ms;
 352                 completed = cur_ops->get_gp_seq();
 353                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 354                                           started, completed);
 355         }
 356         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 357                 udelay(shortdelay_us);
 358                 rtrsp->rt_delay_us = shortdelay_us;
 359         }
 360         if (!preempt_count() &&
 361             !(torture_random(rrsp) % (nrealreaders * 500))) {
 362                 torture_preempt_schedule();  /* QS only if preemptible. */
 363                 rtrsp->rt_preempted = true;
 364         }
 365 }
 366
 367 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 368 {
 369         rcu_read_unlock();
 370 }
 371
 372 /*
 373  * Update callback in the pipe.  This should be invoked after a grace period.
 374  */
 375 static bool
 376 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 377 {
 378         int i;
 379
 380         i = rp->rtort_pipe_count;
 381         if (i > RCU_TORTURE_PIPE_LEN)
 382                 i = RCU_TORTURE_PIPE_LEN;
 383         atomic_inc(&rcu_torture_wcount[i]);
 384         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 385                 rp->rtort_mbtest = 0;
 386                 return true;
 387         }
 388         return false;
 389 }
 390
 391 /*
 392  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 393  * primitives.
 394  */
 395 static void
 396 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 397 {
 398         struct rcu_torture *rp;
 399         struct rcu_torture *rp1;
 400
 401         if (old_rp)
 402                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 403         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 404                 if (rcu_torture_pipe_update_one(rp)) {
 405                         list_del(&rp->rtort_free);
 406                         rcu_torture_free(rp);
 407                 }
 408         }
 409 }
 410
 411 static void
 412 rcu_torture_cb(struct rcu_head *p)
 413 {
 414         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 415
 416         if (torture_must_stop_irq()) {
 417                 /* Test is ending, just drop callbacks on the floor. */
 418                 /* The next initialization will pick up the pieces. */
 419                 return;
 420         }
 421         if (rcu_torture_pipe_update_one(rp))
 422                 rcu_torture_free(rp);
 423         else
 424                 cur_ops->deferred_free(rp);
 425 }
 426
 427 static unsigned long rcu_no_completed(void)
 428 {
 429         return 0;
 430 }
 431
 432 static void rcu_torture_deferred_free(struct rcu_torture *p)
 433 {
 434         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 435 }
 436
 437 static void rcu_sync_torture_init(void)
 438 {
 439         INIT_LIST_HEAD(&rcu_torture_removed);
 440 }
 441
 442 static struct rcu_torture_ops rcu_ops = {
 443         .ttype          = RCU_FLAVOR,
 444         .init           = rcu_sync_torture_init,
 445         .readlock       = rcu_torture_read_lock,
 446         .read_delay     = rcu_read_delay,
 447         .readunlock     = rcu_torture_read_unlock,
 448         .get_gp_seq     = rcu_get_gp_seq,
 449         .gp_diff        = rcu_seq_diff,
 450         .deferred_free  = rcu_torture_deferred_free,
 451         .sync           = synchronize_rcu,
 452         .exp_sync       = synchronize_rcu_expedited,
 453         .get_state      = get_state_synchronize_rcu,
 454         .cond_sync      = cond_synchronize_rcu,
 455         .call           = call_rcu,
 456         .cb_barrier     = rcu_barrier,
 457         .fqs            = rcu_force_quiescent_state,
 458         .stats          = NULL,
 459         .stall_dur      = rcu_jiffies_till_stall_check,
 460         .irq_capable    = 1,
 461         .can_boost      = rcu_can_boost(),
 462         .extendables    = RCUTORTURE_MAX_EXTEND,
 463         .name           = "rcu"
 464 };
 465
 466 /*
 467  * Don't even think about trying any of these in real life!!!
 468  * The names includes "busted", and they really means it!
 469  * The only purpose of these functions is to provide a buggy RCU
 470  * implementation to make sure that rcutorture correctly emits
 471  * buggy-RCU error messages.
 472  */
 473 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 474 {
 475         /* This is a deliberate bug for testing purposes only! */
 476         rcu_torture_cb(&p->rtort_rcu);
 477 }
 478
 479 static void synchronize_rcu_busted(void)
 480 {
 481         /* This is a deliberate bug for testing purposes only! */
 482 }
 483
 484 static void
 485 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 486 {
 487         /* This is a deliberate bug for testing purposes only! */
 488         func(head);
 489 }
 490
 491 static struct rcu_torture_ops rcu_busted_ops = {
 492         .ttype          = INVALID_RCU_FLAVOR,
 493         .init           = rcu_sync_torture_init,
 494         .readlock       = rcu_torture_read_lock,
 495         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 496         .readunlock     = rcu_torture_read_unlock,
 497         .get_gp_seq     = rcu_no_completed,
 498         .deferred_free  = rcu_busted_torture_deferred_free,
 499         .sync           = synchronize_rcu_busted,
 500         .exp_sync       = synchronize_rcu_busted,
 501         .call           = call_rcu_busted,
 502         .cb_barrier     = NULL,
 503         .fqs            = NULL,
 504         .stats          = NULL,
 505         .irq_capable    = 1,
 506         .name           = "busted"
 507 };
 508
 509 /*
 510  * Definitions for srcu torture testing.
 511  */
 512
 513 DEFINE_STATIC_SRCU(srcu_ctl);
 514 static struct srcu_struct srcu_ctld;
 515 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 516
 517 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 518 {
 519         return srcu_read_lock(srcu_ctlp);
 520 }
 521
 522 static void
 523 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 524 {
 525         long delay;
 526         const long uspertick = 1000000 / HZ;
 527         const long longdelay = 10;
 528
 529         /* We want there to be long-running readers, but not all the time. */
 530
 531         delay = torture_random(rrsp) %
 532                 (nrealreaders * 2 * longdelay * uspertick);
 533         if (!delay && in_task()) {
 534                 schedule_timeout_interruptible(longdelay);
 535                 rtrsp->rt_delay_jiffies = longdelay;
 536         } else {
 537                 rcu_read_delay(rrsp, rtrsp);
 538         }
 539 }
 540
 541 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 542 {
 543         srcu_read_unlock(srcu_ctlp, idx);
 544 }
 545
 546 static unsigned long srcu_torture_completed(void)
 547 {
 548         return srcu_batches_completed(srcu_ctlp);
 549 }
 550
 551 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 552 {
 553         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 554 }
 555
 556 static void srcu_torture_synchronize(void)
 557 {
 558         synchronize_srcu(srcu_ctlp);
 559 }
 560
 561 static void srcu_torture_call(struct rcu_head *head,
 562                               rcu_callback_t func)
 563 {
 564         call_srcu(srcu_ctlp, head, func);
 565 }
 566
 567 static void srcu_torture_barrier(void)
 568 {
 569         srcu_barrier(srcu_ctlp);
 570 }
 571
 572 static void srcu_torture_stats(void)
 573 {
 574         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 575 }
 576
 577 static void srcu_torture_synchronize_expedited(void)
 578 {
 579         synchronize_srcu_expedited(srcu_ctlp);
 580 }
 581
 582 static struct rcu_torture_ops srcu_ops = {
 583         .ttype          = SRCU_FLAVOR,
 584         .init           = rcu_sync_torture_init,
 585         .readlock       = srcu_torture_read_lock,
 586         .read_delay     = srcu_read_delay,
 587         .readunlock     = srcu_torture_read_unlock,
 588         .get_gp_seq     = srcu_torture_completed,
 589         .deferred_free  = srcu_torture_deferred_free,
 590         .sync           = srcu_torture_synchronize,
 591         .exp_sync       = srcu_torture_synchronize_expedited,
 592         .call           = srcu_torture_call,
 593         .cb_barrier     = srcu_torture_barrier,
 594         .stats          = srcu_torture_stats,
 595         .irq_capable    = 1,
 596         .name           = "srcu"
 597 };
 598
 599 static void srcu_torture_init(void)
 600 {
 601         rcu_sync_torture_init();
 602         WARN_ON(init_srcu_struct(&srcu_ctld));
 603         srcu_ctlp = &srcu_ctld;
 604 }
 605
 606 static void srcu_torture_cleanup(void)
 607 {
 608         static DEFINE_TORTURE_RANDOM(rand);
 609
 610         if (torture_random(&rand) & 0x800)
 611                 cleanup_srcu_struct(&srcu_ctld);
 612         else
 613                 cleanup_srcu_struct_quiesced(&srcu_ctld);
 614         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 615 }
 616
 617 /* As above, but dynamically allocated. */
 618 static struct rcu_torture_ops srcud_ops = {
 619         .ttype          = SRCU_FLAVOR,
 620         .init           = srcu_torture_init,
 621         .cleanup        = srcu_torture_cleanup,
 622         .readlock       = srcu_torture_read_lock,
 623         .read_delay     = srcu_read_delay,
 624         .readunlock     = srcu_torture_read_unlock,
 625         .get_gp_seq     = srcu_torture_completed,
 626         .deferred_free  = srcu_torture_deferred_free,
 627         .sync           = srcu_torture_synchronize,
 628         .exp_sync       = srcu_torture_synchronize_expedited,
 629         .call           = srcu_torture_call,
 630         .cb_barrier     = srcu_torture_barrier,
 631         .stats          = srcu_torture_stats,
 632         .irq_capable    = 1,
 633         .name           = "srcud"
 634 };
 635
 636 /* As above, but broken due to inappropriate reader extension. */
 637 static struct rcu_torture_ops busted_srcud_ops = {
 638         .ttype          = SRCU_FLAVOR,
 639         .init           = srcu_torture_init,
 640         .cleanup        = srcu_torture_cleanup,
 641         .readlock       = srcu_torture_read_lock,
 642         .read_delay     = rcu_read_delay,
 643         .readunlock     = srcu_torture_read_unlock,
 644         .get_gp_seq     = srcu_torture_completed,
 645         .deferred_free  = srcu_torture_deferred_free,
 646         .sync           = srcu_torture_synchronize,
 647         .exp_sync       = srcu_torture_synchronize_expedited,
 648         .call           = srcu_torture_call,
 649         .cb_barrier     = srcu_torture_barrier,
 650         .stats          = srcu_torture_stats,
 651         .irq_capable    = 1,
 652         .extendables    = RCUTORTURE_MAX_EXTEND,
 653         .name           = "busted_srcud"
 654 };
 655
 656 /*
 657  * Definitions for RCU-tasks torture testing.
 658  */
 659
 660 static int tasks_torture_read_lock(void)
 661 {
 662         return 0;
 663 }
 664
 665 static void tasks_torture_read_unlock(int idx)
 666 {
 667 }
 668
 669 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 670 {
 671         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 672 }
 673
 674 static struct rcu_torture_ops tasks_ops = {
 675         .ttype          = RCU_TASKS_FLAVOR,
 676         .init           = rcu_sync_torture_init,
 677         .readlock       = tasks_torture_read_lock,
 678         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 679         .readunlock     = tasks_torture_read_unlock,
 680         .get_gp_seq     = rcu_no_completed,
 681         .deferred_free  = rcu_tasks_torture_deferred_free,
 682         .sync           = synchronize_rcu_tasks,
 683         .exp_sync       = synchronize_rcu_tasks,
 684         .call           = call_rcu_tasks,
 685         .cb_barrier     = rcu_barrier_tasks,
 686         .fqs            = NULL,
 687         .stats          = NULL,
 688         .irq_capable    = 1,
 689         .name           = "tasks"
 690 };
 691
 692 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 693 {
 694         if (!cur_ops->gp_diff)
 695                 return new - old;
 696         return cur_ops->gp_diff(new, old);
 697 }
 698
 699 static bool __maybe_unused torturing_tasks(void)
 700 {
 701         return cur_ops == &tasks_ops;
 702 }
 703
 704 /*
 705  * RCU torture priority-boost testing.  Runs one real-time thread per
 706  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 707  * spinning waiting for them to be invoked.  If a given callback takes
 708  * too long to be invoked, we assume that priority inversion has occurred.
 709  */
 710
 711 struct rcu_boost_inflight {
 712         struct rcu_head rcu;
 713         int inflight;
 714 };
 715
 716 static void rcu_torture_boost_cb(struct rcu_head *head)
 717 {
 718         struct rcu_boost_inflight *rbip =
 719                 container_of(head, struct rcu_boost_inflight, rcu);
 720
 721         /* Ensure RCU-core accesses precede clearing ->inflight */
 722         smp_store_release(&rbip->inflight, 0);
 723 }
 724
 725 static int old_rt_runtime = -1;
 726
 727 static void rcu_torture_disable_rt_throttle(void)
 728 {
 729         /*
 730          * Disable RT throttling so that rcutorture's boost threads don't get
 731          * throttled. Only possible if rcutorture is built-in otherwise the
 732          * user should manually do this by setting the sched_rt_period_us and
 733          * sched_rt_runtime sysctls.
 734          */
 735         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 736                 return;
 737
 738         old_rt_runtime = sysctl_sched_rt_runtime;
 739         sysctl_sched_rt_runtime = -1;
 740 }
 741
 742 static void rcu_torture_enable_rt_throttle(void)
 743 {
 744         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 745                 return;
 746
 747         sysctl_sched_rt_runtime = old_rt_runtime;
 748         old_rt_runtime = -1;
 749 }
 750
 751 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 752 {
 753         if (end - start > test_boost_duration * HZ - HZ / 2) {
 754                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 755                 n_rcu_torture_boost_failure++;
 756
 757                 return true; /* failed */
 758         }
 759
 760         return false; /* passed */
 761 }
 762
 763 static int rcu_torture_boost(void *arg)
 764 {
 765         unsigned long call_rcu_time;
 766         unsigned long endtime;
 767         unsigned long oldstarttime;
 768         struct rcu_boost_inflight rbi = { .inflight = 0 };
 769         struct sched_param sp;
 770
 771         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 772
 773         /* Set real-time priority. */
 774         sp.sched_priority = 1;
 775         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 776                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 777                 n_rcu_torture_boost_rterror++;
 778         }
 779
 780         init_rcu_head_on_stack(&rbi.rcu);
 781         /* Each pass through the following loop does one boost-test cycle. */
 782         do {
 783                 /* Track if the test failed already in this test interval? */
 784                 bool failed = false;
 785
 786                 /* Increment n_rcu_torture_boosts once per boost-test */
 787                 while (!kthread_should_stop()) {
 788                         if (mutex_trylock(&boost_mutex)) {
 789                                 n_rcu_torture_boosts++;
 790                                 mutex_unlock(&boost_mutex);
 791                                 break;
 792                         }
 793                         schedule_timeout_uninterruptible(1);
 794                 }
 795                 if (kthread_should_stop())
 796                         goto checkwait;
 797
 798                 /* Wait for the next test interval. */
 799                 oldstarttime = boost_starttime;
 800                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 801                         schedule_timeout_interruptible(oldstarttime - jiffies);
 802                         stutter_wait("rcu_torture_boost");
 803                         if (torture_must_stop())
 804                                 goto checkwait;
 805                 }
 806
 807                 /* Do one boost-test interval. */
 808                 endtime = oldstarttime + test_boost_duration * HZ;
 809                 call_rcu_time = jiffies;
 810                 while (ULONG_CMP_LT(jiffies, endtime)) {
 811                         /* If we don't have a callback in flight, post one. */
 812                         if (!smp_load_acquire(&rbi.inflight)) {
 813                                 /* RCU core before ->inflight = 1. */
 814                                 smp_store_release(&rbi.inflight, 1);
 815                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 816                                 /* Check if the boost test failed */
 817                                 failed = failed ||
 818                                          rcu_torture_boost_failed(call_rcu_time,
 819                                                                  jiffies);
 820                                 call_rcu_time = jiffies;
 821                         }
 822                         stutter_wait("rcu_torture_boost");
 823                         if (torture_must_stop())
 824                                 goto checkwait;
 825                 }
 826
 827                 /*
 828                  * If boost never happened, then inflight will always be 1, in
 829                  * this case the boost check would never happen in the above
 830                  * loop so do another one here.
 831                  */
 832                 if (!failed && smp_load_acquire(&rbi.inflight))
 833                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 834
 835                 /*
 836                  * Set the start time of the next test interval.
 837                  * Yes, this is vulnerable to long delays, but such
 838                  * delays simply cause a false negative for the next
 839                  * interval.  Besides, we are running at RT priority,
 840                  * so delays should be relatively rare.
 841                  */
 842                 while (oldstarttime == boost_starttime &&
 843                        !kthread_should_stop()) {
 844                         if (mutex_trylock(&boost_mutex)) {
 845                                 boost_starttime = jiffies +
 846                                                   test_boost_interval * HZ;
 847                                 mutex_unlock(&boost_mutex);
 848                                 break;
 849                         }
 850                         schedule_timeout_uninterruptible(1);
 851                 }
 852
 853                 /* Go do the stutter. */
 854 checkwait:      stutter_wait("rcu_torture_boost");
 855         } while (!torture_must_stop());
 856
 857         /* Clean up and exit. */
 858         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 859                 torture_shutdown_absorb("rcu_torture_boost");
 860                 schedule_timeout_uninterruptible(1);
 861         }
 862         destroy_rcu_head_on_stack(&rbi.rcu);
 863         torture_kthread_stopping("rcu_torture_boost");
 864         return 0;
 865 }
 866
 867 /*
 868  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 869  * bursts of calls to force_quiescent_state(), increasing the probability
 870  * of occurrence of some important types of race conditions.
 871  */
 872 static int
 873 rcu_torture_fqs(void *arg)
 874 {
 875         unsigned long fqs_resume_time;
 876         int fqs_burst_remaining;
 877
 878         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 879         do {
 880                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 881                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 882                        !kthread_should_stop()) {
 883                         schedule_timeout_interruptible(1);
 884                 }
 885                 fqs_burst_remaining = fqs_duration;
 886                 while (fqs_burst_remaining > 0 &&
 887                        !kthread_should_stop()) {
 888                         cur_ops->fqs();
 889                         udelay(fqs_holdoff);
 890                         fqs_burst_remaining -= fqs_holdoff;
 891                 }
 892                 stutter_wait("rcu_torture_fqs");
 893         } while (!torture_must_stop());
 894         torture_kthread_stopping("rcu_torture_fqs");
 895         return 0;
 896 }
 897
 898 /*
 899  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 900  * for that pointed to by rcu_torture_current, freeing the old structure
 901  * after a series of grace periods (the "pipeline").
 902  */
 903 static int
 904 rcu_torture_writer(void *arg)
 905 {
 906         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 907         int expediting = 0;
 908         unsigned long gp_snap;
 909         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 910         bool gp_sync1 = gp_sync;
 911         int i;
 912         struct rcu_torture *rp;
 913         struct rcu_torture *old_rp;
 914         static DEFINE_TORTURE_RANDOM(rand);
 915         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 916                            RTWS_COND_GET, RTWS_SYNC };
 917         int nsynctypes = 0;
 918
 919         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 920         if (!can_expedite)
 921                 pr_alert("%s" TORTURE_FLAG
 922                          " GP expediting controlled from boot/sysfs for %s.\n",
 923                          torture_type, cur_ops->name);
 924
 925         /* Initialize synctype[] array.  If none set, take default. */
 926         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 927                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 928         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 929                 synctype[nsynctypes++] = RTWS_COND_GET;
 930                 pr_info("%s: Testing conditional GPs.\n", __func__);
 931         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 932                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 933         }
 934         if (gp_exp1 && cur_ops->exp_sync) {
 935                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 936                 pr_info("%s: Testing expedited GPs.\n", __func__);
 937         } else if (gp_exp && !cur_ops->exp_sync) {
 938                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 939         }
 940         if (gp_normal1 && cur_ops->deferred_free) {
 941                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 942                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 943         } else if (gp_normal && !cur_ops->deferred_free) {
 944                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 945         }
 946         if (gp_sync1 && cur_ops->sync) {
 947                 synctype[nsynctypes++] = RTWS_SYNC;
 948                 pr_info("%s: Testing normal GPs.\n", __func__);
 949         } else if (gp_sync && !cur_ops->sync) {
 950                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 951         }
 952         if (WARN_ONCE(nsynctypes == 0,
 953                       "rcu_torture_writer: No update-side primitives.\n")) {
 954                 /*
 955                  * No updates primitives, so don't try updating.
 956                  * The resulting test won't be testing much, hence the
 957                  * above WARN_ONCE().
 958                  */
 959                 rcu_torture_writer_state = RTWS_STOPPING;
 960                 torture_kthread_stopping("rcu_torture_writer");
 961         }
 962
 963         do {
 964                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 965                 schedule_timeout_uninterruptible(1);
 966                 rp = rcu_torture_alloc();
 967                 if (rp == NULL)
 968                         continue;
 969                 rp->rtort_pipe_count = 0;
 970                 rcu_torture_writer_state = RTWS_DELAY;
 971                 udelay(torture_random(&rand) & 0x3ff);
 972                 rcu_torture_writer_state = RTWS_REPLACE;
 973                 old_rp = rcu_dereference_check(rcu_torture_current,
 974                                                current == writer_task);
 975                 rp->rtort_mbtest = 1;
 976                 rcu_assign_pointer(rcu_torture_current, rp);
 977                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 978                 if (old_rp) {
 979                         i = old_rp->rtort_pipe_count;
 980                         if (i > RCU_TORTURE_PIPE_LEN)
 981                                 i = RCU_TORTURE_PIPE_LEN;
 982                         atomic_inc(&rcu_torture_wcount[i]);
 983                         old_rp->rtort_pipe_count++;
 984                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 985                         case RTWS_DEF_FREE:
 986                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 987                                 cur_ops->deferred_free(old_rp);
 988                                 break;
 989                         case RTWS_EXP_SYNC:
 990                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 991                                 cur_ops->exp_sync();
 992                                 rcu_torture_pipe_update(old_rp);
 993                                 break;
 994                         case RTWS_COND_GET:
 995                                 rcu_torture_writer_state = RTWS_COND_GET;
 996                                 gp_snap = cur_ops->get_state();
 997                                 i = torture_random(&rand) % 16;
 998                                 if (i != 0)
 999                                         schedule_timeout_interruptible(i);
1000                                 udelay(torture_random(&rand) % 1000);
1001                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1002                                 cur_ops->cond_sync(gp_snap);
1003                                 rcu_torture_pipe_update(old_rp);
1004                                 break;
1005                         case RTWS_SYNC:
1006                                 rcu_torture_writer_state = RTWS_SYNC;
1007                                 cur_ops->sync();
1008                                 rcu_torture_pipe_update(old_rp);
1009                                 break;
1010                         default:
1011                                 WARN_ON_ONCE(1);
1012                                 break;
1013                         }
1014                 }
1015                 WRITE_ONCE(rcu_torture_current_version,
1016                            rcu_torture_current_version + 1);
1017                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1018                 if (can_expedite &&
1019                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1020                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1021                         if (expediting >= 0)
1022                                 rcu_expedite_gp();
1023                         else
1024                                 rcu_unexpedite_gp();
1025                         if (++expediting > 3)
1026                                 expediting = -expediting;
1027                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1028                         can_expedite = !rcu_gp_is_expedited() &&
1029                                        !rcu_gp_is_normal();
1030                 }
1031                 rcu_torture_writer_state = RTWS_STUTTER;
1032                 if (stutter_wait("rcu_torture_writer"))
1033                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1034                                 if (list_empty(&rcu_tortures[i].rtort_free))
1035                                         WARN_ON_ONCE(1);
1036         } while (!torture_must_stop());
1037         /* Reset expediting back to unexpedited. */
1038         if (expediting > 0)
1039                 expediting = -expediting;
1040         while (can_expedite && expediting++ < 0)
1041                 rcu_unexpedite_gp();
1042         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1043         if (!can_expedite)
1044                 pr_alert("%s" TORTURE_FLAG
1045                          " Dynamic grace-period expediting was disabled.\n",
1046                          torture_type);
1047         rcu_torture_writer_state = RTWS_STOPPING;
1048         torture_kthread_stopping("rcu_torture_writer");
1049         return 0;
1050 }
1051
1052 /*
1053  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1054  * delay between calls.
1055  */
1056 static int
1057 rcu_torture_fakewriter(void *arg)
1058 {
1059         DEFINE_TORTURE_RANDOM(rand);
1060
1061         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1062         set_user_nice(current, MAX_NICE);
1063
1064         do {
1065                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1066                 udelay(torture_random(&rand) & 0x3ff);
1067                 if (cur_ops->cb_barrier != NULL &&
1068                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1069                         cur_ops->cb_barrier();
1070                 } else if (gp_normal == gp_exp) {
1071                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1072                                 cur_ops->sync();
1073                         else if (cur_ops->exp_sync)
1074                                 cur_ops->exp_sync();
1075                 } else if (gp_normal && cur_ops->sync) {
1076                         cur_ops->sync();
1077                 } else if (cur_ops->exp_sync) {
1078                         cur_ops->exp_sync();
1079                 }
1080                 stutter_wait("rcu_torture_fakewriter");
1081         } while (!torture_must_stop());
1082
1083         torture_kthread_stopping("rcu_torture_fakewriter");
1084         return 0;
1085 }
1086
1087 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1088 {
1089         kfree(rhp);
1090 }
1091
1092 /*
1093  * Do one extension of an RCU read-side critical section using the
1094  * current reader state in readstate (set to zero for initial entry
1095  * to extended critical section), set the new state as specified by
1096  * newstate (set to zero for final exit from extended critical section),
1097  * and random-number-generator state in trsp.  If this is neither the
1098  * beginning or end of the critical section and if there was actually a
1099  * change, do a ->read_delay().
1100  */
1101 static void rcutorture_one_extend(int *readstate, int newstate,
1102                                   struct torture_random_state *trsp,
1103                                   struct rt_read_seg *rtrsp)
1104 {
1105         int idxnew = -1;
1106         int idxold = *readstate;
1107         int statesnew = ~*readstate & newstate;
1108         int statesold = *readstate & ~newstate;
1109
1110         WARN_ON_ONCE(idxold < 0);
1111         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1112         rtrsp->rt_readstate = newstate;
1113
1114         /* First, put new protection in place to avoid critical-section gap. */
1115         if (statesnew & RCUTORTURE_RDR_BH)
1116                 local_bh_disable();
1117         if (statesnew & RCUTORTURE_RDR_IRQ)
1118                 local_irq_disable();
1119         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1120                 preempt_disable();
1121         if (statesnew & RCUTORTURE_RDR_RBH)
1122                 rcu_read_lock_bh();
1123         if (statesnew & RCUTORTURE_RDR_SCHED)
1124                 rcu_read_lock_sched();
1125         if (statesnew & RCUTORTURE_RDR_RCU)
1126                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1127
1128         /* Next, remove old protection, irq first due to bh conflict. */
1129         if (statesold & RCUTORTURE_RDR_IRQ)
1130                 local_irq_enable();
1131         if (statesold & RCUTORTURE_RDR_BH)
1132                 local_bh_enable();
1133         if (statesold & RCUTORTURE_RDR_PREEMPT)
1134                 preempt_enable();
1135         if (statesold & RCUTORTURE_RDR_RBH)
1136                 rcu_read_unlock_bh();
1137         if (statesold & RCUTORTURE_RDR_SCHED)
1138                 rcu_read_unlock_sched();
1139         if (statesold & RCUTORTURE_RDR_RCU)
1140                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1141
1142         /* Delay if neither beginning nor end and there was a change. */
1143         if ((statesnew || statesold) && *readstate && newstate)
1144                 cur_ops->read_delay(trsp, rtrsp);
1145
1146         /* Update the reader state. */
1147         if (idxnew == -1)
1148                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1149         WARN_ON_ONCE(idxnew < 0);
1150         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1151         *readstate = idxnew | newstate;
1152         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1153         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1154 }
1155
1156 /* Return the biggest extendables mask given current RCU and boot parameters. */
1157 static int rcutorture_extend_mask_max(void)
1158 {
1159         int mask;
1160
1161         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1162         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1163         mask = mask | RCUTORTURE_RDR_RCU;
1164         return mask;
1165 }
1166
1167 /* Return a random protection state mask, but with at least one bit set. */
1168 static int
1169 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1170 {
1171         int mask = rcutorture_extend_mask_max();
1172         unsigned long randmask1 = torture_random(trsp) >> 8;
1173         unsigned long randmask2 = randmask1 >> 3;
1174
1175         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1176         /* Most of the time lots of bits, half the time only one bit. */
1177         if (!(randmask1 & 0x7))
1178                 mask = mask & randmask2;
1179         else
1180                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1181         /* Can't enable bh w/irq disabled. */
1182         if ((mask & RCUTORTURE_RDR_IRQ) &&
1183             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1184              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1185                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1186         if ((mask & RCUTORTURE_RDR_IRQ) &&
1187             !(mask & cur_ops->ext_irq_conflict) &&
1188             (oldmask & cur_ops->ext_irq_conflict))
1189                 mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
1190         return mask ?: RCUTORTURE_RDR_RCU;
1191 }
1192
1193 /*
1194  * Do a randomly selected number of extensions of an existing RCU read-side
1195  * critical section.
1196  */
1197 static struct rt_read_seg *
1198 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1199                        struct rt_read_seg *rtrsp)
1200 {
1201         int i;
1202         int j;
1203         int mask = rcutorture_extend_mask_max();
1204
1205         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1206         if (!((mask - 1) & mask))
1207                 return rtrsp;  /* Current RCU reader not extendable. */
1208         /* Bias towards larger numbers of loops. */
1209         i = (torture_random(trsp) >> 3);
1210         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1211         for (j = 0; j < i; j++) {
1212                 mask = rcutorture_extend_mask(*readstate, trsp);
1213                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1214         }
1215         return &rtrsp[j];
1216 }
1217
1218 /*
1219  * Do one read-side critical section, returning false if there was
1220  * no data to read.  Can be invoked both from process context and
1221  * from a timer handler.
1222  */
1223 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1224 {
1225         int i;
1226         unsigned long started;
1227         unsigned long completed;
1228         int newstate;
1229         struct rcu_torture *p;
1230         int pipe_count;
1231         int readstate = 0;
1232         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1233         struct rt_read_seg *rtrsp = &rtseg[0];
1234         struct rt_read_seg *rtrsp1;
1235         unsigned long long ts;
1236
1237         newstate = rcutorture_extend_mask(readstate, trsp);
1238         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1239         started = cur_ops->get_gp_seq();
1240         ts = rcu_trace_clock_local();
1241         p = rcu_dereference_check(rcu_torture_current,
1242                                   rcu_read_lock_bh_held() ||
1243                                   rcu_read_lock_sched_held() ||
1244                                   srcu_read_lock_held(srcu_ctlp) ||
1245                                   torturing_tasks());
1246         if (p == NULL) {
1247                 /* Wait for rcu_torture_writer to get underway */
1248                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1249                 return false;
1250         }
1251         if (p->rtort_mbtest == 0)
1252                 atomic_inc(&n_rcu_torture_mberror);
1253         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1254         preempt_disable();
1255         pipe_count = p->rtort_pipe_count;
1256         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1257                 /* Should not happen, but... */
1258                 pipe_count = RCU_TORTURE_PIPE_LEN;
1259         }
1260         completed = cur_ops->get_gp_seq();
1261         if (pipe_count > 1) {
1262                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1263                                           ts, started, completed);
1264                 rcu_ftrace_dump(DUMP_ALL);
1265         }
1266         __this_cpu_inc(rcu_torture_count[pipe_count]);
1267         completed = rcutorture_seq_diff(completed, started);
1268         if (completed > RCU_TORTURE_PIPE_LEN) {
1269                 /* Should not happen, but... */
1270                 completed = RCU_TORTURE_PIPE_LEN;
1271         }
1272         __this_cpu_inc(rcu_torture_batch[completed]);
1273         preempt_enable();
1274         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1275         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1276
1277         /* If error or close call, record the sequence of reader protections. */
1278         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1279                 i = 0;
1280                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1281                         err_segs[i++] = *rtrsp1;
1282                 rt_read_nsegs = i;
1283         }
1284
1285         return true;
1286 }
1287
1288 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1289
1290 /*
1291  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1292  * incrementing the corresponding element of the pipeline array.  The
1293  * counter in the element should never be greater than 1, otherwise, the
1294  * RCU implementation is broken.
1295  */
1296 static void rcu_torture_timer(struct timer_list *unused)
1297 {
1298         atomic_long_inc(&n_rcu_torture_timers);
1299         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1300
1301         /* Test call_rcu() invocation from interrupt handler. */
1302         if (cur_ops->call) {
1303                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1304
1305                 if (rhp)
1306                         cur_ops->call(rhp, rcu_torture_timer_cb);
1307         }
1308 }
1309
1310 /*
1311  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1312  * incrementing the corresponding element of the pipeline array.  The
1313  * counter in the element should never be greater than 1, otherwise, the
1314  * RCU implementation is broken.
1315  */
1316 static int
1317 rcu_torture_reader(void *arg)
1318 {
1319         unsigned long lastsleep = jiffies;
1320         long myid = (long)arg;
1321         int mynumonline = myid;
1322         DEFINE_TORTURE_RANDOM(rand);
1323         struct timer_list t;
1324
1325         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1326         set_user_nice(current, MAX_NICE);
1327         if (irqreader && cur_ops->irq_capable)
1328                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1329
1330         do {
1331                 if (irqreader && cur_ops->irq_capable) {
1332                         if (!timer_pending(&t))
1333                                 mod_timer(&t, jiffies + 1);
1334                 }
1335                 if (!rcu_torture_one_read(&rand))
1336                         schedule_timeout_interruptible(HZ);
1337                 if (time_after(jiffies, lastsleep)) {
1338                         schedule_timeout_interruptible(1);
1339                         lastsleep = jiffies + 10;
1340                 }
1341                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1342                         schedule_timeout_interruptible(HZ / 5);
1343                 stutter_wait("rcu_torture_reader");
1344         } while (!torture_must_stop());
1345         if (irqreader && cur_ops->irq_capable) {
1346                 del_timer_sync(&t);
1347                 destroy_timer_on_stack(&t);
1348         }
1349         torture_kthread_stopping("rcu_torture_reader");
1350         return 0;
1351 }
1352
1353 /*
1354  * Print torture statistics.  Caller must ensure that there is only
1355  * one call to this function at a given time!!!  This is normally
1356  * accomplished by relying on the module system to only have one copy
1357  * of the module loaded, and then by giving the rcu_torture_stats
1358  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1359  * thread is not running).
1360  */
1361 static void
1362 rcu_torture_stats_print(void)
1363 {
1364         int cpu;
1365         int i;
1366         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1367         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1368         static unsigned long rtcv_snap = ULONG_MAX;
1369         static bool splatted;
1370         struct task_struct *wtp;
1371
1372         for_each_possible_cpu(cpu) {
1373                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1374                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1375                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1376                 }
1377         }
1378         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1379                 if (pipesummary[i] != 0)
1380                         break;
1381         }
1382
1383         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1384         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1385                 rcu_torture_current,
1386                 rcu_torture_current_version,
1387                 list_empty(&rcu_torture_freelist),
1388                 atomic_read(&n_rcu_torture_alloc),
1389                 atomic_read(&n_rcu_torture_alloc_fail),
1390                 atomic_read(&n_rcu_torture_free));
1391         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1392                 atomic_read(&n_rcu_torture_mberror),
1393                 n_rcu_torture_barrier_error,
1394                 n_rcu_torture_boost_ktrerror,
1395                 n_rcu_torture_boost_rterror);
1396         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1397                 n_rcu_torture_boost_failure,
1398                 n_rcu_torture_boosts,
1399                 atomic_long_read(&n_rcu_torture_timers));
1400         torture_onoff_stats();
1401         pr_cont("barrier: %ld/%ld:%ld\n",
1402                 n_barrier_successes,
1403                 n_barrier_attempts,
1404                 n_rcu_torture_barrier_error);
1405
1406         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1407         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1408             n_rcu_torture_barrier_error != 0 ||
1409             n_rcu_torture_boost_ktrerror != 0 ||
1410             n_rcu_torture_boost_rterror != 0 ||
1411             n_rcu_torture_boost_failure != 0 ||
1412             i > 1) {
1413                 pr_cont("%s", "!!! ");
1414                 atomic_inc(&n_rcu_torture_error);
1415                 WARN_ON_ONCE(1);
1416         }
1417         pr_cont("Reader Pipe: ");
1418         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1419                 pr_cont(" %ld", pipesummary[i]);
1420         pr_cont("\n");
1421
1422         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1423         pr_cont("Reader Batch: ");
1424         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1425                 pr_cont(" %ld", batchsummary[i]);
1426         pr_cont("\n");
1427
1428         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1429         pr_cont("Free-Block Circulation: ");
1430         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1431                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1432         }
1433         pr_cont("\n");
1434
1435         if (cur_ops->stats)
1436                 cur_ops->stats();
1437         if (rtcv_snap == rcu_torture_current_version &&
1438             rcu_torture_current != NULL) {
1439                 int __maybe_unused flags = 0;
1440                 unsigned long __maybe_unused gp_seq = 0;
1441
1442                 rcutorture_get_gp_data(cur_ops->ttype,
1443                                        &flags, &gp_seq);
1444                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1445                                         &flags, &gp_seq);
1446                 wtp = READ_ONCE(writer_task);
1447                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1448                          rcu_torture_writer_state_getname(),
1449                          rcu_torture_writer_state, gp_seq, flags,
1450                          wtp == NULL ? ~0UL : wtp->state,
1451                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1452                 if (!splatted && wtp) {
1453                         sched_show_task(wtp);
1454                         splatted = true;
1455                 }
1456                 show_rcu_gp_kthreads();
1457                 rcu_ftrace_dump(DUMP_ALL);
1458         }
1459         rtcv_snap = rcu_torture_current_version;
1460 }
1461
1462 /*
1463  * Periodically prints torture statistics, if periodic statistics printing
1464  * was specified via the stat_interval module parameter.
1465  */
1466 static int
1467 rcu_torture_stats(void *arg)
1468 {
1469         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1470         do {
1471                 schedule_timeout_interruptible(stat_interval * HZ);
1472                 rcu_torture_stats_print();
1473                 torture_shutdown_absorb("rcu_torture_stats");
1474         } while (!torture_must_stop());
1475         torture_kthread_stopping("rcu_torture_stats");
1476         return 0;
1477 }
1478
1479 static void
1480 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1481 {
1482         pr_alert("%s" TORTURE_FLAG
1483                  "--- %s: nreaders=%d nfakewriters=%d "
1484                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1485                  "shuffle_interval=%d stutter=%d irqreader=%d "
1486                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1487                  "test_boost=%d/%d test_boost_interval=%d "
1488                  "test_boost_duration=%d shutdown_secs=%d "
1489                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1490                  "n_barrier_cbs=%d "
1491                  "onoff_interval=%d onoff_holdoff=%d\n",
1492                  torture_type, tag, nrealreaders, nfakewriters,
1493                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1494                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1495                  test_boost, cur_ops->can_boost,
1496                  test_boost_interval, test_boost_duration, shutdown_secs,
1497                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1498                  n_barrier_cbs,
1499                  onoff_interval, onoff_holdoff);
1500 }
1501
1502 static int rcutorture_booster_cleanup(unsigned int cpu)
1503 {
1504         struct task_struct *t;
1505
1506         if (boost_tasks[cpu] == NULL)
1507                 return 0;
1508         mutex_lock(&boost_mutex);
1509         t = boost_tasks[cpu];
1510         boost_tasks[cpu] = NULL;
1511         rcu_torture_enable_rt_throttle();
1512         mutex_unlock(&boost_mutex);
1513
1514         /* This must be outside of the mutex, otherwise deadlock! */
1515         torture_stop_kthread(rcu_torture_boost, t);
1516         return 0;
1517 }
1518
1519 static int rcutorture_booster_init(unsigned int cpu)
1520 {
1521         int retval;
1522
1523         if (boost_tasks[cpu] != NULL)
1524                 return 0;  /* Already created, nothing more to do. */
1525
1526         /* Don't allow time recalculation while creating a new task. */
1527         mutex_lock(&boost_mutex);
1528         rcu_torture_disable_rt_throttle();
1529         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1530         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1531                                                   cpu_to_node(cpu),
1532                                                   "rcu_torture_boost");
1533         if (IS_ERR(boost_tasks[cpu])) {
1534                 retval = PTR_ERR(boost_tasks[cpu]);
1535                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1536                 n_rcu_torture_boost_ktrerror++;
1537                 boost_tasks[cpu] = NULL;
1538                 mutex_unlock(&boost_mutex);
1539                 return retval;
1540         }
1541         kthread_bind(boost_tasks[cpu], cpu);
1542         wake_up_process(boost_tasks[cpu]);
1543         mutex_unlock(&boost_mutex);
1544         return 0;
1545 }
1546
1547 /*
1548  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1549  * induces a CPU stall for the time specified by stall_cpu.
1550  */
1551 static int rcu_torture_stall(void *args)
1552 {
1553         unsigned long stop_at;
1554
1555         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1556         if (stall_cpu_holdoff > 0) {
1557                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1558                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1559                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1560         }
1561         if (!kthread_should_stop()) {
1562                 stop_at = ktime_get_seconds() + stall_cpu;
1563                 /* RCU CPU stall is expected behavior in following code. */
1564                 rcu_read_lock();
1565                 if (stall_cpu_irqsoff)
1566                         local_irq_disable();
1567                 else
1568                         preempt_disable();
1569                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1570                          smp_processor_id());
1571                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1572                                     stop_at))
1573                         continue;  /* Induce RCU CPU stall warning. */
1574                 if (stall_cpu_irqsoff)
1575                         local_irq_enable();
1576                 else
1577                         preempt_enable();
1578                 rcu_read_unlock();
1579                 pr_alert("rcu_torture_stall end.\n");
1580         }
1581         torture_shutdown_absorb("rcu_torture_stall");
1582         while (!kthread_should_stop())
1583                 schedule_timeout_interruptible(10 * HZ);
1584         return 0;
1585 }
1586
1587 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1588 static int __init rcu_torture_stall_init(void)
1589 {
1590         if (stall_cpu <= 0)
1591                 return 0;
1592         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1593 }
1594
1595 /* State structure for forward-progress self-propagating RCU callback. */
1596 struct fwd_cb_state {
1597         struct rcu_head rh;
1598         int stop;
1599 };
1600
1601 /*
1602  * Forward-progress self-propagating RCU callback function.  Because
1603  * callbacks run from softirq, this function is an implicit RCU read-side
1604  * critical section.
1605  */
1606 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1607 {
1608         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1609
1610         if (READ_ONCE(fcsp->stop)) {
1611                 WRITE_ONCE(fcsp->stop, 2);
1612                 return;
1613         }
1614         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1615 }
1616
1617 /* State for continuous-flood RCU callbacks. */
1618 struct rcu_fwd_cb {
1619         struct rcu_head rh;
1620         struct rcu_fwd_cb *rfc_next;
1621         int rfc_gps;
1622 };
1623 static DEFINE_SPINLOCK(rcu_fwd_lock);
1624 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1625 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1626 static long n_launders_cb;
1627 static unsigned long rcu_fwd_startat;
1628 static bool rcu_fwd_emergency_stop;
1629 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1630 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1631 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1632 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1633 static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)];
1634
1635 static void rcu_torture_fwd_cb_hist(void)
1636 {
1637         int i;
1638         int j;
1639
1640         for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1641                 if (n_launders_hist[i] > 0)
1642                         break;
1643         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1644                  __func__, jiffies - rcu_fwd_startat);
1645         for (j = 0; j <= i; j++)
1646                 pr_cont(" %ds/%d: %ld",
1647                         j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j]);
1648         pr_cont("\n");
1649 }
1650
1651 /* Callback function for continuous-flood RCU callbacks. */
1652 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1653 {
1654         unsigned long flags;
1655         int i;
1656         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1657         struct rcu_fwd_cb **rfcpp;
1658
1659         rfcp->rfc_next = NULL;
1660         rfcp->rfc_gps++;
1661         spin_lock_irqsave(&rcu_fwd_lock, flags);
1662         rfcpp = rcu_fwd_cb_tail;
1663         rcu_fwd_cb_tail = &rfcp->rfc_next;
1664         WRITE_ONCE(*rfcpp, rfcp);
1665         WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1666         i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1667         if (i >= ARRAY_SIZE(n_launders_hist))
1668                 i = ARRAY_SIZE(n_launders_hist) - 1;
1669         n_launders_hist[i]++;
1670         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1671 }
1672
1673 /*
1674  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1675  * test is over or because we hit an OOM event.
1676  */
1677 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1678 {
1679         unsigned long flags;
1680         unsigned long freed = 0;
1681         struct rcu_fwd_cb *rfcp;
1682
1683         for (;;) {
1684                 spin_lock_irqsave(&rcu_fwd_lock, flags);
1685                 rfcp = rcu_fwd_cb_head;
1686                 if (!rfcp)
1687                         break;
1688                 rcu_fwd_cb_head = rfcp->rfc_next;
1689                 if (!rcu_fwd_cb_head)
1690                         rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1691                 spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1692                 kfree(rfcp);
1693                 freed++;
1694         }
1695         spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1696         return freed;
1697 }
1698
1699 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1700 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1701 {
1702         unsigned long cver;
1703         unsigned long dur;
1704         struct fwd_cb_state fcs;
1705         unsigned long gps;
1706         int idx;
1707         int sd;
1708         int sd4;
1709         bool selfpropcb = false;
1710         unsigned long stopat;
1711         static DEFINE_TORTURE_RANDOM(trs);
1712
1713         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1714                 init_rcu_head_on_stack(&fcs.rh);
1715                 selfpropcb = true;
1716         }
1717
1718         /* Tight loop containing cond_resched(). */
1719         if  (selfpropcb) {
1720                 WRITE_ONCE(fcs.stop, 0);
1721                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1722         }
1723         cver = READ_ONCE(rcu_torture_current_version);
1724         gps = cur_ops->get_gp_seq();
1725         sd = cur_ops->stall_dur() + 1;
1726         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1727         dur = sd4 + torture_random(&trs) % (sd - sd4);
1728         WRITE_ONCE(rcu_fwd_startat, jiffies);
1729         stopat = rcu_fwd_startat + dur;
1730         while (time_before(jiffies, stopat) &&
1731                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1732                 idx = cur_ops->readlock();
1733                 udelay(10);
1734                 cur_ops->readunlock(idx);
1735                 if (!fwd_progress_need_resched || need_resched())
1736                         cond_resched();
1737         }
1738         (*tested_tries)++;
1739         if (!time_before(jiffies, stopat) &&
1740             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1741                 (*tested)++;
1742                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1743                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1744                 WARN_ON(!cver && gps < 2);
1745                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1746         }
1747         if (selfpropcb) {
1748                 WRITE_ONCE(fcs.stop, 1);
1749                 cur_ops->sync(); /* Wait for running CB to complete. */
1750                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1751         }
1752
1753         if (selfpropcb) {
1754                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1755                 destroy_rcu_head_on_stack(&fcs.rh);
1756         }
1757 }
1758
1759 /* Carry out call_rcu() forward-progress testing. */
1760 static void rcu_torture_fwd_prog_cr(void)
1761 {
1762         unsigned long cver;
1763         unsigned long gps;
1764         int i;
1765         long n_launders;
1766         long n_launders_cb_snap;
1767         long n_launders_sa;
1768         long n_max_cbs;
1769         long n_max_gps;
1770         struct rcu_fwd_cb *rfcp;
1771         struct rcu_fwd_cb *rfcpn;
1772         unsigned long stopat;
1773         unsigned long stoppedat;
1774
1775         if (READ_ONCE(rcu_fwd_emergency_stop))
1776                 return; /* Get out of the way quickly, no GP wait! */
1777
1778         /* Loop continuously posting RCU callbacks. */
1779         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1780         cur_ops->sync(); /* Later readers see above write. */
1781         WRITE_ONCE(rcu_fwd_startat, jiffies);
1782         stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1783         n_launders = 0;
1784         n_launders_cb = 0;
1785         n_launders_sa = 0;
1786         n_max_cbs = 0;
1787         n_max_gps = 0;
1788         for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1789                 n_launders_hist[i] = 0;
1790         cver = READ_ONCE(rcu_torture_current_version);
1791         gps = cur_ops->get_gp_seq();
1792         while (time_before(jiffies, stopat) &&
1793                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1794                 rfcp = READ_ONCE(rcu_fwd_cb_head);
1795                 rfcpn = NULL;
1796                 if (rfcp)
1797                         rfcpn = READ_ONCE(rfcp->rfc_next);
1798                 if (rfcpn) {
1799                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1800                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1801                                 break;
1802                         rcu_fwd_cb_head = rfcpn;
1803                         n_launders++;
1804                         n_launders_sa++;
1805                 } else {
1806                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1807                         if (WARN_ON_ONCE(!rfcp)) {
1808                                 schedule_timeout_interruptible(1);
1809                                 continue;
1810                         }
1811                         n_max_cbs++;
1812                         n_launders_sa = 0;
1813                         rfcp->rfc_gps = 0;
1814                 }
1815                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1816                 cond_resched();
1817         }
1818         stoppedat = jiffies;
1819         n_launders_cb_snap = READ_ONCE(n_launders_cb);
1820         cver = READ_ONCE(rcu_torture_current_version) - cver;
1821         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1822         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1823         (void)rcu_torture_fwd_prog_cbfree();
1824
1825         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1826         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
1827                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1828                 pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
1829                          __func__,
1830                          stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1831                          n_launders + n_max_cbs - n_launders_cb_snap,
1832                          n_launders, n_launders_sa,
1833                          n_max_gps, n_max_cbs, cver, gps);
1834                 rcu_torture_fwd_cb_hist();
1835         }
1836 }
1837
1838
1839 /*
1840  * OOM notifier, but this only prints diagnostic information for the
1841  * current forward-progress test.
1842  */
1843 static int rcutorture_oom_notify(struct notifier_block *self,
1844                                  unsigned long notused, void *nfreed)
1845 {
1846         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1847              __func__);
1848         rcu_torture_fwd_cb_hist();
1849         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2));
1850         WRITE_ONCE(rcu_fwd_emergency_stop, true);
1851         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1852         pr_info("%s: Freed %lu RCU callbacks.\n",
1853                 __func__, rcu_torture_fwd_prog_cbfree());
1854         rcu_barrier();
1855         pr_info("%s: Freed %lu RCU callbacks.\n",
1856                 __func__, rcu_torture_fwd_prog_cbfree());
1857         rcu_barrier();
1858         pr_info("%s: Freed %lu RCU callbacks.\n",
1859                 __func__, rcu_torture_fwd_prog_cbfree());
1860         smp_mb(); /* Frees before return to avoid redoing OOM. */
1861         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1862         pr_info("%s returning after OOM processing.\n", __func__);
1863         return NOTIFY_OK;
1864 }
1865
1866 static struct notifier_block rcutorture_oom_nb = {
1867         .notifier_call = rcutorture_oom_notify
1868 };
1869
1870 /* Carry out grace-period forward-progress testing. */
1871 static int rcu_torture_fwd_prog(void *args)
1872 {
1873         int tested = 0;
1874         int tested_tries = 0;
1875
1876         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1877         rcu_bind_current_to_nocb();
1878         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1879                 set_user_nice(current, MAX_NICE);
1880         do {
1881                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1882                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
1883                 register_oom_notifier(&rcutorture_oom_nb);
1884                 rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1885                 rcu_torture_fwd_prog_cr();
1886                 unregister_oom_notifier(&rcutorture_oom_nb);
1887
1888                 /* Avoid slow periods, better to test when busy. */
1889                 stutter_wait("rcu_torture_fwd_prog");
1890         } while (!torture_must_stop());
1891         /* Short runs might not contain a valid forward-progress attempt. */
1892         WARN_ON(!tested && tested_tries >= 5);
1893         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1894         torture_kthread_stopping("rcu_torture_fwd_prog");
1895         return 0;
1896 }
1897
1898 /* If forward-progress checking is requested and feasible, spawn the thread. */
1899 static int __init rcu_torture_fwd_prog_init(void)
1900 {
1901         if (!fwd_progress)
1902                 return 0; /* Not requested, so don't do it. */
1903         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1904             cur_ops == &rcu_busted_ops) {
1905                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1906                 return 0;
1907         }
1908         if (stall_cpu > 0) {
1909                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1910                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1911                         return -EINVAL; /* In module, can fail back to user. */
1912                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
1913                 return 0;
1914         }
1915         if (fwd_progress_holdoff <= 0)
1916                 fwd_progress_holdoff = 1;
1917         if (fwd_progress_div <= 0)
1918                 fwd_progress_div = 4;
1919         return torture_create_kthread(rcu_torture_fwd_prog,
1920                                       NULL, fwd_prog_task);
1921 }
1922
1923 /* Callback function for RCU barrier testing. */
1924 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1925 {
1926         atomic_inc(&barrier_cbs_invoked);
1927 }
1928
1929 /* kthread function to register callbacks used to test RCU barriers. */
1930 static int rcu_torture_barrier_cbs(void *arg)
1931 {
1932         long myid = (long)arg;
1933         bool lastphase = 0;
1934         bool newphase;
1935         struct rcu_head rcu;
1936
1937         init_rcu_head_on_stack(&rcu);
1938         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1939         set_user_nice(current, MAX_NICE);
1940         do {
1941                 wait_event(barrier_cbs_wq[myid],
1942                            (newphase =
1943                             smp_load_acquire(&barrier_phase)) != lastphase ||
1944                            torture_must_stop());
1945                 lastphase = newphase;
1946                 if (torture_must_stop())
1947                         break;
1948                 /*
1949                  * The above smp_load_acquire() ensures barrier_phase load
1950                  * is ordered before the following ->call().
1951                  */
1952                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1953                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1954                 local_irq_enable();
1955                 if (atomic_dec_and_test(&barrier_cbs_count))
1956                         wake_up(&barrier_wq);
1957         } while (!torture_must_stop());
1958         if (cur_ops->cb_barrier != NULL)
1959                 cur_ops->cb_barrier();
1960         destroy_rcu_head_on_stack(&rcu);
1961         torture_kthread_stopping("rcu_torture_barrier_cbs");
1962         return 0;
1963 }
1964
1965 /* kthread function to drive and coordinate RCU barrier testing. */
1966 static int rcu_torture_barrier(void *arg)
1967 {
1968         int i;
1969
1970         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1971         do {
1972                 atomic_set(&barrier_cbs_invoked, 0);
1973                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1974                 /* Ensure barrier_phase ordered after prior assignments. */
1975                 smp_store_release(&barrier_phase, !barrier_phase);
1976                 for (i = 0; i < n_barrier_cbs; i++)
1977                         wake_up(&barrier_cbs_wq[i]);
1978                 wait_event(barrier_wq,
1979                            atomic_read(&barrier_cbs_count) == 0 ||
1980                            torture_must_stop());
1981                 if (torture_must_stop())
1982                         break;
1983                 n_barrier_attempts++;
1984                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1985                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1986                         n_rcu_torture_barrier_error++;
1987                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1988                                atomic_read(&barrier_cbs_invoked),
1989                                n_barrier_cbs);
1990                         WARN_ON_ONCE(1);
1991                 } else {
1992                         n_barrier_successes++;
1993                 }
1994                 schedule_timeout_interruptible(HZ / 10);
1995         } while (!torture_must_stop());
1996         torture_kthread_stopping("rcu_torture_barrier");
1997         return 0;
1998 }
1999
2000 /* Initialize RCU barrier testing. */
2001 static int rcu_torture_barrier_init(void)
2002 {
2003         int i;
2004         int ret;
2005
2006         if (n_barrier_cbs <= 0)
2007                 return 0;
2008         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2009                 pr_alert("%s" TORTURE_FLAG
2010                          " Call or barrier ops missing for %s,\n",
2011                          torture_type, cur_ops->name);
2012                 pr_alert("%s" TORTURE_FLAG
2013                          " RCU barrier testing omitted from run.\n",
2014                          torture_type);
2015                 return 0;
2016         }
2017         atomic_set(&barrier_cbs_count, 0);
2018         atomic_set(&barrier_cbs_invoked, 0);
2019         barrier_cbs_tasks =
2020                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2021                         GFP_KERNEL);
2022         barrier_cbs_wq =
2023                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2024         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2025                 return -ENOMEM;
2026         for (i = 0; i < n_barrier_cbs; i++) {
2027                 init_waitqueue_head(&barrier_cbs_wq[i]);
2028                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2029                                              (void *)(long)i,
2030                                              barrier_cbs_tasks[i]);
2031                 if (ret)
2032                         return ret;
2033         }
2034         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2035 }
2036
2037 /* Clean up after RCU barrier testing. */
2038 static void rcu_torture_barrier_cleanup(void)
2039 {
2040         int i;
2041
2042         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2043         if (barrier_cbs_tasks != NULL) {
2044                 for (i = 0; i < n_barrier_cbs; i++)
2045                         torture_stop_kthread(rcu_torture_barrier_cbs,
2046                                              barrier_cbs_tasks[i]);
2047                 kfree(barrier_cbs_tasks);
2048                 barrier_cbs_tasks = NULL;
2049         }
2050         if (barrier_cbs_wq != NULL) {
2051                 kfree(barrier_cbs_wq);
2052                 barrier_cbs_wq = NULL;
2053         }
2054 }
2055
2056 static bool rcu_torture_can_boost(void)
2057 {
2058         static int boost_warn_once;
2059         int prio;
2060
2061         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2062                 return false;
2063
2064         prio = rcu_get_gp_kthreads_prio();
2065         if (!prio)
2066                 return false;
2067
2068         if (prio < 2) {
2069                 if (boost_warn_once  == 1)
2070                         return false;
2071
2072                 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);
2073                 boost_warn_once = 1;
2074                 return false;
2075         }
2076
2077         return true;
2078 }
2079
2080 static enum cpuhp_state rcutor_hp;
2081
2082 static void
2083 rcu_torture_cleanup(void)
2084 {
2085         int firsttime;
2086         int flags = 0;
2087         unsigned long gp_seq = 0;
2088         int i;
2089
2090         if (torture_cleanup_begin()) {
2091                 if (cur_ops->cb_barrier != NULL)
2092                         cur_ops->cb_barrier();
2093                 return;
2094         }
2095
2096         rcu_torture_barrier_cleanup();
2097         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2098         torture_stop_kthread(rcu_torture_stall, stall_task);
2099         torture_stop_kthread(rcu_torture_writer, writer_task);
2100
2101         if (reader_tasks) {
2102                 for (i = 0; i < nrealreaders; i++)
2103                         torture_stop_kthread(rcu_torture_reader,
2104                                              reader_tasks[i]);
2105                 kfree(reader_tasks);
2106         }
2107         rcu_torture_current = NULL;
2108
2109         if (fakewriter_tasks) {
2110                 for (i = 0; i < nfakewriters; i++) {
2111                         torture_stop_kthread(rcu_torture_fakewriter,
2112                                              fakewriter_tasks[i]);
2113                 }
2114                 kfree(fakewriter_tasks);
2115                 fakewriter_tasks = NULL;
2116         }
2117
2118         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2119         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2120         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2121                  cur_ops->name, gp_seq, flags);
2122         torture_stop_kthread(rcu_torture_stats, stats_task);
2123         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2124         if (rcu_torture_can_boost())
2125                 cpuhp_remove_state(rcutor_hp);
2126
2127         /*
2128          * Wait for all RCU callbacks to fire, then do torture-type-specific
2129          * cleanup operations.
2130          */
2131         if (cur_ops->cb_barrier != NULL)
2132                 cur_ops->cb_barrier();
2133         if (cur_ops->cleanup != NULL)
2134                 cur_ops->cleanup();
2135
2136         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2137
2138         if (err_segs_recorded) {
2139                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2140                 if (rt_read_nsegs == 0)
2141                         pr_alert("\t: No segments recorded!!!\n");
2142                 firsttime = 1;
2143                 for (i = 0; i < rt_read_nsegs; i++) {
2144                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2145                         if (err_segs[i].rt_delay_jiffies != 0) {
2146                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2147                                         err_segs[i].rt_delay_jiffies);
2148                                 firsttime = 0;
2149                         }
2150                         if (err_segs[i].rt_delay_ms != 0) {
2151                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2152                                         err_segs[i].rt_delay_ms);
2153                                 firsttime = 0;
2154                         }
2155                         if (err_segs[i].rt_delay_us != 0) {
2156                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2157                                         err_segs[i].rt_delay_us);
2158                                 firsttime = 0;
2159                         }
2160                         pr_cont("%s\n",
2161                                 err_segs[i].rt_preempted ? "preempted" : "");
2162
2163                 }
2164         }
2165         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2166                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2167         else if (torture_onoff_failures())
2168                 rcu_torture_print_module_parms(cur_ops,
2169                                                "End of test: RCU_HOTPLUG");
2170         else
2171                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2172         torture_cleanup_end();
2173 }
2174
2175 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2176 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2177 {
2178 }
2179
2180 static void rcu_torture_err_cb(struct rcu_head *rhp)
2181 {
2182         /*
2183          * This -might- happen due to race conditions, but is unlikely.
2184          * The scenario that leads to this happening is that the
2185          * first of the pair of duplicate callbacks is queued,
2186          * someone else starts a grace period that includes that
2187          * callback, then the second of the pair must wait for the
2188          * next grace period.  Unlikely, but can happen.  If it
2189          * does happen, the debug-objects subsystem won't have splatted.
2190          */
2191         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2192 }
2193 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2194
2195 /*
2196  * Verify that double-free causes debug-objects to complain, but only
2197  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2198  * cannot be carried out.
2199  */
2200 static void rcu_test_debug_objects(void)
2201 {
2202 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2203         struct rcu_head rh1;
2204         struct rcu_head rh2;
2205
2206         init_rcu_head_on_stack(&rh1);
2207         init_rcu_head_on_stack(&rh2);
2208         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2209
2210         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2211         preempt_disable(); /* Prevent preemption from interrupting test. */
2212         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2213         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2214         local_irq_disable(); /* Make it harder to start a new grace period. */
2215         call_rcu(&rh2, rcu_torture_leak_cb);
2216         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2217         local_irq_enable();
2218         rcu_read_unlock();
2219         preempt_enable();
2220
2221         /* Wait for them all to get done so we can safely return. */
2222         rcu_barrier();
2223         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2224         destroy_rcu_head_on_stack(&rh1);
2225         destroy_rcu_head_on_stack(&rh2);
2226 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2227         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2228 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2229 }
2230
2231 static int __init
2232 rcu_torture_init(void)
2233 {
2234         long i;
2235         int cpu;
2236         int firsterr = 0;
2237         static struct rcu_torture_ops *torture_ops[] = {
2238                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2239                 &busted_srcud_ops, &tasks_ops,
2240         };
2241
2242         if (!torture_init_begin(torture_type, verbose))
2243                 return -EBUSY;
2244
2245         /* Process args and tell the world that the torturer is on the job. */
2246         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2247                 cur_ops = torture_ops[i];
2248                 if (strcmp(torture_type, cur_ops->name) == 0)
2249                         break;
2250         }
2251         if (i == ARRAY_SIZE(torture_ops)) {
2252                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2253                          torture_type);
2254                 pr_alert("rcu-torture types:");
2255                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2256                         pr_cont(" %s", torture_ops[i]->name);
2257                 pr_cont("\n");
2258                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2259                 firsterr = -EINVAL;
2260                 goto unwind;
2261         }
2262         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2263                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2264                 fqs_duration = 0;
2265         }
2266         if (cur_ops->init)
2267                 cur_ops->init();
2268
2269         if (nreaders >= 0) {
2270                 nrealreaders = nreaders;
2271         } else {
2272                 nrealreaders = num_online_cpus() - 2 - nreaders;
2273                 if (nrealreaders <= 0)
2274                         nrealreaders = 1;
2275         }
2276         rcu_torture_print_module_parms(cur_ops, "Start of test");
2277
2278         /* Set up the freelist. */
2279
2280         INIT_LIST_HEAD(&rcu_torture_freelist);
2281         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2282                 rcu_tortures[i].rtort_mbtest = 0;
2283                 list_add_tail(&rcu_tortures[i].rtort_free,
2284                               &rcu_torture_freelist);
2285         }
2286
2287         /* Initialize the statistics so that each run gets its own numbers. */
2288
2289         rcu_torture_current = NULL;
2290         rcu_torture_current_version = 0;
2291         atomic_set(&n_rcu_torture_alloc, 0);
2292         atomic_set(&n_rcu_torture_alloc_fail, 0);
2293         atomic_set(&n_rcu_torture_free, 0);
2294         atomic_set(&n_rcu_torture_mberror, 0);
2295         atomic_set(&n_rcu_torture_error, 0);
2296         n_rcu_torture_barrier_error = 0;
2297         n_rcu_torture_boost_ktrerror = 0;
2298         n_rcu_torture_boost_rterror = 0;
2299         n_rcu_torture_boost_failure = 0;
2300         n_rcu_torture_boosts = 0;
2301         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2302                 atomic_set(&rcu_torture_wcount[i], 0);
2303         for_each_possible_cpu(cpu) {
2304                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2305                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2306                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2307                 }
2308         }
2309         err_segs_recorded = 0;
2310         rt_read_nsegs = 0;
2311
2312         /* Start up the kthreads. */
2313
2314         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2315                                           writer_task);
2316         if (firsterr)
2317                 goto unwind;
2318         if (nfakewriters > 0) {
2319                 fakewriter_tasks = kcalloc(nfakewriters,
2320                                            sizeof(fakewriter_tasks[0]),
2321                                            GFP_KERNEL);
2322                 if (fakewriter_tasks == NULL) {
2323                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2324                         firsterr = -ENOMEM;
2325                         goto unwind;
2326                 }
2327         }
2328         for (i = 0; i < nfakewriters; i++) {
2329                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2330                                                   NULL, fakewriter_tasks[i]);
2331                 if (firsterr)
2332                         goto unwind;
2333         }
2334         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2335                                GFP_KERNEL);
2336         if (reader_tasks == NULL) {
2337                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2338                 firsterr = -ENOMEM;
2339                 goto unwind;
2340         }
2341         for (i = 0; i < nrealreaders; i++) {
2342                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2343                                                   reader_tasks[i]);
2344                 if (firsterr)
2345                         goto unwind;
2346         }
2347         if (stat_interval > 0) {
2348                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2349                                                   stats_task);
2350                 if (firsterr)
2351                         goto unwind;
2352         }
2353         if (test_no_idle_hz && shuffle_interval > 0) {
2354                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2355                 if (firsterr)
2356                         goto unwind;
2357         }
2358         if (stutter < 0)
2359                 stutter = 0;
2360         if (stutter) {
2361                 firsterr = torture_stutter_init(stutter * HZ);
2362                 if (firsterr)
2363                         goto unwind;
2364         }
2365         if (fqs_duration < 0)
2366                 fqs_duration = 0;
2367         if (fqs_duration) {
2368                 /* Create the fqs thread */
2369                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2370                                                   fqs_task);
2371                 if (firsterr)
2372                         goto unwind;
2373         }
2374         if (test_boost_interval < 1)
2375                 test_boost_interval = 1;
2376         if (test_boost_duration < 2)
2377                 test_boost_duration = 2;
2378         if (rcu_torture_can_boost()) {
2379
2380                 boost_starttime = jiffies + test_boost_interval * HZ;
2381
2382                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2383                                              rcutorture_booster_init,
2384                                              rcutorture_booster_cleanup);
2385                 if (firsterr < 0)
2386                         goto unwind;
2387                 rcutor_hp = firsterr;
2388         }
2389         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2390         if (firsterr)
2391                 goto unwind;
2392         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
2393         if (firsterr)
2394                 goto unwind;
2395         firsterr = rcu_torture_stall_init();
2396         if (firsterr)
2397                 goto unwind;
2398         firsterr = rcu_torture_fwd_prog_init();
2399         if (firsterr)
2400                 goto unwind;
2401         firsterr = rcu_torture_barrier_init();
2402         if (firsterr)
2403                 goto unwind;
2404         if (object_debug)
2405                 rcu_test_debug_objects();
2406         torture_init_end();
2407         return 0;
2408
2409 unwind:
2410         torture_init_end();
2411         rcu_torture_cleanup();
2412         return firsterr;
2413 }
2414
2415 module_init(rcu_torture_init);
2416 module_exit(rcu_torture_cleanup);