kernel/rcu/rcutorture.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Read-Copy Update module-based torture test facility
   4  *
   5  * Copyright (C) IBM Corporation, 2005, 2006
   6  *
   7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
   8  *        Josh Triplett <josh@joshtriplett.org>
   9  *
  10  * See also:  Documentation/RCU/torture.txt
  11  */
  12
  13 #define pr_fmt(fmt) fmt
  14
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/kthread.h>
  20 #include <linux/err.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/smp.h>
  23 #include <linux/rcupdate_wait.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/sched/signal.h>
  26 #include <uapi/linux/sched/types.h>
  27 #include <linux/atomic.h>
  28 #include <linux/bitops.h>
  29 #include <linux/completion.h>
  30 #include <linux/moduleparam.h>
  31 #include <linux/percpu.h>
  32 #include <linux/notifier.h>
  33 #include <linux/reboot.h>
  34 #include <linux/freezer.h>
  35 #include <linux/cpu.h>
  36 #include <linux/delay.h>
  37 #include <linux/stat.h>
  38 #include <linux/srcu.h>
  39 #include <linux/slab.h>
  40 #include <linux/trace_clock.h>
  41 #include <asm/byteorder.h>
  42 #include <linux/torture.h>
  43 #include <linux/vmalloc.h>
  44 #include <linux/sched/debug.h>
  45 #include <linux/sched/sysctl.h>
  46 #include <linux/oom.h>
  47 #include <linux/tick.h>
  48 #include <linux/rcupdate_trace.h>
  49
  50 #include "rcu.h"
  51
  52 MODULE_LICENSE("GPL");
  53 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  54
  55 #ifndef data_race
  56 #define data_race(expr)                                                 \
  57         ({                                                              \
  58                 expr;                                                   \
  59         })
  60 #endif
  61 #ifndef ASSERT_EXCLUSIVE_WRITER
  62 #define ASSERT_EXCLUSIVE_WRITER(var) do { } while (0)
  63 #endif
  64 #ifndef ASSERT_EXCLUSIVE_ACCESS
  65 #define ASSERT_EXCLUSIVE_ACCESS(var) do { } while (0)
  66 #endif
  67
  68 /* Bits for ->extendables field, extendables param, and related definitions. */
  69 #define RCUTORTURE_RDR_SHIFT     8      /* Put SRCU index in upper bits. */
  70 #define RCUTORTURE_RDR_MASK      ((1 << RCUTORTURE_RDR_SHIFT) - 1)
  71 #define RCUTORTURE_RDR_BH        0x01   /* Extend readers by disabling bh. */
  72 #define RCUTORTURE_RDR_IRQ       0x02   /*  ... disabling interrupts. */
  73 #define RCUTORTURE_RDR_PREEMPT   0x04   /*  ... disabling preemption. */
  74 #define RCUTORTURE_RDR_RBH       0x08   /*  ... rcu_read_lock_bh(). */
  75 #define RCUTORTURE_RDR_SCHED     0x10   /*  ... rcu_read_lock_sched(). */
  76 #define RCUTORTURE_RDR_RCU       0x20   /*  ... entering another RCU reader. */
  77 #define RCUTORTURE_RDR_NBITS     6      /* Number of bits defined above. */
  78 #define RCUTORTURE_MAX_EXTEND    \
  79         (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
  80          RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
  81 #define RCUTORTURE_RDR_MAX_LOOPS 0x7    /* Maximum reader extensions. */
  82                                         /* Must be power of two minus one. */
  83 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
  84
  85 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
  86               "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
  87 torture_param(int, fqs_duration, 0,
  88               "Duration of fqs bursts (us), 0 to disable");
  89 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  90 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  91 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
  92 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
  93 torture_param(int, fwd_progress_holdoff, 60,
  94               "Time between forward-progress tests (s)");
  95 torture_param(bool, fwd_progress_need_resched, 1,
  96               "Hide cond_resched() behind need_resched()");
  97 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  98 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  99 torture_param(bool, gp_normal, false,
 100              "Use normal (non-expedited) GP wait primitives");
 101 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
 102 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
 103 torture_param(int, n_barrier_cbs, 0,
 104              "# of callbacks/kthreads for barrier testing");
 105 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
 106 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 107 torture_param(int, object_debug, 0,
 108              "Enable debug-object double call_rcu() testing");
 109 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
 110 torture_param(int, onoff_interval, 0,
 111              "Time between CPU hotplugs (jiffies), 0=disable");
 112 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
 113 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
 114 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
 115 torture_param(int, stall_cpu_holdoff, 10,
 116              "Time to wait before starting stall (s).");
 117 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
 118 torture_param(int, stall_cpu_block, 0, "Sleep while stalling.");
 119 torture_param(int, stall_gp_kthread, 0,
 120               "Grace-period kthread stall duration (s).");
 121 torture_param(int, stat_interval, 60,
 122              "Number of seconds between stats printk()s");
 123 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
 124 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 125 torture_param(int, test_boost_duration, 4,
 126              "Duration of each boost test, seconds.");
 127 torture_param(int, test_boost_interval, 7,
 128              "Interval between boost tests, seconds.");
 129 torture_param(bool, test_no_idle_hz, true,
 130              "Test support for tickless idle CPUs");
 131 torture_param(int, verbose, 1,
 132              "Enable verbose debugging printk()s");
 133
 134 static char *torture_type = "rcu";
 135 module_param(torture_type, charp, 0444);
 136 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 137
 138 static int nrealreaders;
 139 static struct task_struct *writer_task;
 140 static struct task_struct **fakewriter_tasks;
 141 static struct task_struct **reader_tasks;
 142 static struct task_struct *stats_task;
 143 static struct task_struct *fqs_task;
 144 static struct task_struct *boost_tasks[NR_CPUS];
 145 static struct task_struct *stall_task;
 146 static struct task_struct *fwd_prog_task;
 147 static struct task_struct **barrier_cbs_tasks;
 148 static struct task_struct *barrier_task;
 149
 150 #define RCU_TORTURE_PIPE_LEN 10
 151
 152 struct rcu_torture {
 153         struct rcu_head rtort_rcu;
 154         int rtort_pipe_count;
 155         struct list_head rtort_free;
 156         int rtort_mbtest;
 157 };
 158
 159 static LIST_HEAD(rcu_torture_freelist);
 160 static struct rcu_torture __rcu *rcu_torture_current;
 161 static unsigned long rcu_torture_current_version;
 162 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 163 static DEFINE_SPINLOCK(rcu_torture_lock);
 164 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 165 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 166 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 167 static atomic_t n_rcu_torture_alloc;
 168 static atomic_t n_rcu_torture_alloc_fail;
 169 static atomic_t n_rcu_torture_free;
 170 static atomic_t n_rcu_torture_mberror;
 171 static atomic_t n_rcu_torture_error;
 172 static long n_rcu_torture_barrier_error;
 173 static long n_rcu_torture_boost_ktrerror;
 174 static long n_rcu_torture_boost_rterror;
 175 static long n_rcu_torture_boost_failure;
 176 static long n_rcu_torture_boosts;
 177 static atomic_long_t n_rcu_torture_timers;
 178 static long n_barrier_attempts;
 179 static long n_barrier_successes; /* did rcu_barrier test succeed? */
 180 static struct list_head rcu_torture_removed;
 181 static unsigned long shutdown_jiffies;
 182
 183 static int rcu_torture_writer_state;
 184 #define RTWS_FIXED_DELAY        0
 185 #define RTWS_DELAY              1
 186 #define RTWS_REPLACE            2
 187 #define RTWS_DEF_FREE           3
 188 #define RTWS_EXP_SYNC           4
 189 #define RTWS_COND_GET           5
 190 #define RTWS_COND_SYNC          6
 191 #define RTWS_SYNC               7
 192 #define RTWS_STUTTER            8
 193 #define RTWS_STOPPING           9
 194 static const char * const rcu_torture_writer_state_names[] = {
 195         "RTWS_FIXED_DELAY",
 196         "RTWS_DELAY",
 197         "RTWS_REPLACE",
 198         "RTWS_DEF_FREE",
 199         "RTWS_EXP_SYNC",
 200         "RTWS_COND_GET",
 201         "RTWS_COND_SYNC",
 202         "RTWS_SYNC",
 203         "RTWS_STUTTER",
 204         "RTWS_STOPPING",
 205 };
 206
 207 /* Record reader segment types and duration for first failing read. */
 208 struct rt_read_seg {
 209         int rt_readstate;
 210         unsigned long rt_delay_jiffies;
 211         unsigned long rt_delay_ms;
 212         unsigned long rt_delay_us;
 213         bool rt_preempted;
 214 };
 215 static int err_segs_recorded;
 216 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
 217 static int rt_read_nsegs;
 218
 219 static const char *rcu_torture_writer_state_getname(void)
 220 {
 221         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 222
 223         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 224                 return "???";
 225         return rcu_torture_writer_state_names[i];
 226 }
 227
 228 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 229 #define rcu_can_boost() 1
 230 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 231 #define rcu_can_boost() 0
 232 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 233
 234 #ifdef CONFIG_RCU_TRACE
 235 static u64 notrace rcu_trace_clock_local(void)
 236 {
 237         u64 ts = trace_clock_local();
 238
 239         (void)do_div(ts, NSEC_PER_USEC);
 240         return ts;
 241 }
 242 #else /* #ifdef CONFIG_RCU_TRACE */
 243 static u64 notrace rcu_trace_clock_local(void)
 244 {
 245         return 0ULL;
 246 }
 247 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 248
 249 /*
 250  * Stop aggressive CPU-hog tests a bit before the end of the test in order
 251  * to avoid interfering with test shutdown.
 252  */
 253 static bool shutdown_time_arrived(void)
 254 {
 255         return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
 256 }
 257
 258 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 259 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 260                                         /*  and boost task create/destroy. */
 261 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 262 static bool barrier_phase;              /* Test phase. */
 263 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 264 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 265 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 266
 267 static bool rcu_fwd_cb_nodelay;         /* Short rcu_torture_delay() delays. */
 268
 269 /*
 270  * Allocate an element from the rcu_tortures pool.
 271  */
 272 static struct rcu_torture *
 273 rcu_torture_alloc(void)
 274 {
 275         struct list_head *p;
 276
 277         spin_lock_bh(&rcu_torture_lock);
 278         if (list_empty(&rcu_torture_freelist)) {
 279                 atomic_inc(&n_rcu_torture_alloc_fail);
 280                 spin_unlock_bh(&rcu_torture_lock);
 281                 return NULL;
 282         }
 283         atomic_inc(&n_rcu_torture_alloc);
 284         p = rcu_torture_freelist.next;
 285         list_del_init(p);
 286         spin_unlock_bh(&rcu_torture_lock);
 287         return container_of(p, struct rcu_torture, rtort_free);
 288 }
 289
 290 /*
 291  * Free an element to the rcu_tortures pool.
 292  */
 293 static void
 294 rcu_torture_free(struct rcu_torture *p)
 295 {
 296         atomic_inc(&n_rcu_torture_free);
 297         spin_lock_bh(&rcu_torture_lock);
 298         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 299         spin_unlock_bh(&rcu_torture_lock);
 300 }
 301
 302 /*
 303  * Operations vector for selecting different types of tests.
 304  */
 305
 306 struct rcu_torture_ops {
 307         int ttype;
 308         void (*init)(void);
 309         void (*cleanup)(void);
 310         int (*readlock)(void);
 311         void (*read_delay)(struct torture_random_state *rrsp,
 312                            struct rt_read_seg *rtrsp);
 313         void (*readunlock)(int idx);
 314         unsigned long (*get_gp_seq)(void);
 315         unsigned long (*gp_diff)(unsigned long new, unsigned long old);
 316         void (*deferred_free)(struct rcu_torture *p);
 317         void (*sync)(void);
 318         void (*exp_sync)(void);
 319         unsigned long (*get_state)(void);
 320         void (*cond_sync)(unsigned long oldstate);
 321         call_rcu_func_t call;
 322         void (*cb_barrier)(void);
 323         void (*fqs)(void);
 324         void (*stats)(void);
 325         int (*stall_dur)(void);
 326         int irq_capable;
 327         int can_boost;
 328         int extendables;
 329         int slow_gps;
 330         const char *name;
 331 };
 332
 333 static struct rcu_torture_ops *cur_ops;
 334
 335 /*
 336  * Definitions for rcu torture testing.
 337  */
 338
 339 static int rcu_torture_read_lock(void) __acquires(RCU)
 340 {
 341         rcu_read_lock();
 342         return 0;
 343 }
 344
 345 static void
 346 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 347 {
 348         unsigned long started;
 349         unsigned long completed;
 350         const unsigned long shortdelay_us = 200;
 351         unsigned long longdelay_ms = 300;
 352         unsigned long long ts;
 353
 354         /* We want a short delay sometimes to make a reader delay the grace
 355          * period, and we want a long delay occasionally to trigger
 356          * force_quiescent_state. */
 357
 358         if (!READ_ONCE(rcu_fwd_cb_nodelay) &&
 359             !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 360                 started = cur_ops->get_gp_seq();
 361                 ts = rcu_trace_clock_local();
 362                 if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
 363                         longdelay_ms = 5; /* Avoid triggering BH limits. */
 364                 mdelay(longdelay_ms);
 365                 rtrsp->rt_delay_ms = longdelay_ms;
 366                 completed = cur_ops->get_gp_seq();
 367                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 368                                           started, completed);
 369         }
 370         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 371                 udelay(shortdelay_us);
 372                 rtrsp->rt_delay_us = shortdelay_us;
 373         }
 374         if (!preempt_count() &&
 375             !(torture_random(rrsp) % (nrealreaders * 500))) {
 376                 torture_preempt_schedule();  /* QS only if preemptible. */
 377                 rtrsp->rt_preempted = true;
 378         }
 379 }
 380
 381 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 382 {
 383         rcu_read_unlock();
 384 }
 385
 386 /*
 387  * Update callback in the pipe.  This should be invoked after a grace period.
 388  */
 389 static bool
 390 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 391 {
 392         int i;
 393
 394         i = READ_ONCE(rp->rtort_pipe_count);
 395         if (i > RCU_TORTURE_PIPE_LEN)
 396                 i = RCU_TORTURE_PIPE_LEN;
 397         atomic_inc(&rcu_torture_wcount[i]);
 398         WRITE_ONCE(rp->rtort_pipe_count, i + 1);
 399         if (rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 400                 rp->rtort_mbtest = 0;
 401                 return true;
 402         }
 403         return false;
 404 }
 405
 406 /*
 407  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 408  * primitives.
 409  */
 410 static void
 411 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 412 {
 413         struct rcu_torture *rp;
 414         struct rcu_torture *rp1;
 415
 416         if (old_rp)
 417                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 418         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 419                 if (rcu_torture_pipe_update_one(rp)) {
 420                         list_del(&rp->rtort_free);
 421                         rcu_torture_free(rp);
 422                 }
 423         }
 424 }
 425
 426 static void
 427 rcu_torture_cb(struct rcu_head *p)
 428 {
 429         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 430
 431         if (torture_must_stop_irq()) {
 432                 /* Test is ending, just drop callbacks on the floor. */
 433                 /* The next initialization will pick up the pieces. */
 434                 return;
 435         }
 436         if (rcu_torture_pipe_update_one(rp))
 437                 rcu_torture_free(rp);
 438         else
 439                 cur_ops->deferred_free(rp);
 440 }
 441
 442 static unsigned long rcu_no_completed(void)
 443 {
 444         return 0;
 445 }
 446
 447 static void rcu_torture_deferred_free(struct rcu_torture *p)
 448 {
 449         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 450 }
 451
 452 static void rcu_sync_torture_init(void)
 453 {
 454         INIT_LIST_HEAD(&rcu_torture_removed);
 455 }
 456
 457 static struct rcu_torture_ops rcu_ops = {
 458         .ttype          = RCU_FLAVOR,
 459         .init           = rcu_sync_torture_init,
 460         .readlock       = rcu_torture_read_lock,
 461         .read_delay     = rcu_read_delay,
 462         .readunlock     = rcu_torture_read_unlock,
 463         .get_gp_seq     = rcu_get_gp_seq,
 464         .gp_diff        = rcu_seq_diff,
 465         .deferred_free  = rcu_torture_deferred_free,
 466         .sync           = synchronize_rcu,
 467         .exp_sync       = synchronize_rcu_expedited,
 468         .get_state      = get_state_synchronize_rcu,
 469         .cond_sync      = cond_synchronize_rcu,
 470         .call           = call_rcu,
 471         .cb_barrier     = rcu_barrier,
 472         .fqs            = rcu_force_quiescent_state,
 473         .stats          = NULL,
 474         .stall_dur      = rcu_jiffies_till_stall_check,
 475         .irq_capable    = 1,
 476         .can_boost      = rcu_can_boost(),
 477         .extendables    = RCUTORTURE_MAX_EXTEND,
 478         .name           = "rcu"
 479 };
 480
 481 /*
 482  * Don't even think about trying any of these in real life!!!
 483  * The names includes "busted", and they really means it!
 484  * The only purpose of these functions is to provide a buggy RCU
 485  * implementation to make sure that rcutorture correctly emits
 486  * buggy-RCU error messages.
 487  */
 488 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 489 {
 490         /* This is a deliberate bug for testing purposes only! */
 491         rcu_torture_cb(&p->rtort_rcu);
 492 }
 493
 494 static void synchronize_rcu_busted(void)
 495 {
 496         /* This is a deliberate bug for testing purposes only! */
 497 }
 498
 499 static void
 500 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 501 {
 502         /* This is a deliberate bug for testing purposes only! */
 503         func(head);
 504 }
 505
 506 static struct rcu_torture_ops rcu_busted_ops = {
 507         .ttype          = INVALID_RCU_FLAVOR,
 508         .init           = rcu_sync_torture_init,
 509         .readlock       = rcu_torture_read_lock,
 510         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 511         .readunlock     = rcu_torture_read_unlock,
 512         .get_gp_seq     = rcu_no_completed,
 513         .deferred_free  = rcu_busted_torture_deferred_free,
 514         .sync           = synchronize_rcu_busted,
 515         .exp_sync       = synchronize_rcu_busted,
 516         .call           = call_rcu_busted,
 517         .cb_barrier     = NULL,
 518         .fqs            = NULL,
 519         .stats          = NULL,
 520         .irq_capable    = 1,
 521         .name           = "busted"
 522 };
 523
 524 /*
 525  * Definitions for srcu torture testing.
 526  */
 527
 528 DEFINE_STATIC_SRCU(srcu_ctl);
 529 static struct srcu_struct srcu_ctld;
 530 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 531
 532 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 533 {
 534         return srcu_read_lock(srcu_ctlp);
 535 }
 536
 537 static void
 538 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 539 {
 540         long delay;
 541         const long uspertick = 1000000 / HZ;
 542         const long longdelay = 10;
 543
 544         /* We want there to be long-running readers, but not all the time. */
 545
 546         delay = torture_random(rrsp) %
 547                 (nrealreaders * 2 * longdelay * uspertick);
 548         if (!delay && in_task()) {
 549                 schedule_timeout_interruptible(longdelay);
 550                 rtrsp->rt_delay_jiffies = longdelay;
 551         } else {
 552                 rcu_read_delay(rrsp, rtrsp);
 553         }
 554 }
 555
 556 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 557 {
 558         srcu_read_unlock(srcu_ctlp, idx);
 559 }
 560
 561 static unsigned long srcu_torture_completed(void)
 562 {
 563         return srcu_batches_completed(srcu_ctlp);
 564 }
 565
 566 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 567 {
 568         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 569 }
 570
 571 static void srcu_torture_synchronize(void)
 572 {
 573         synchronize_srcu(srcu_ctlp);
 574 }
 575
 576 static void srcu_torture_call(struct rcu_head *head,
 577                               rcu_callback_t func)
 578 {
 579         call_srcu(srcu_ctlp, head, func);
 580 }
 581
 582 static void srcu_torture_barrier(void)
 583 {
 584         srcu_barrier(srcu_ctlp);
 585 }
 586
 587 static void srcu_torture_stats(void)
 588 {
 589         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 590 }
 591
 592 static void srcu_torture_synchronize_expedited(void)
 593 {
 594         synchronize_srcu_expedited(srcu_ctlp);
 595 }
 596
 597 static struct rcu_torture_ops srcu_ops = {
 598         .ttype          = SRCU_FLAVOR,
 599         .init           = rcu_sync_torture_init,
 600         .readlock       = srcu_torture_read_lock,
 601         .read_delay     = srcu_read_delay,
 602         .readunlock     = srcu_torture_read_unlock,
 603         .get_gp_seq     = srcu_torture_completed,
 604         .deferred_free  = srcu_torture_deferred_free,
 605         .sync           = srcu_torture_synchronize,
 606         .exp_sync       = srcu_torture_synchronize_expedited,
 607         .call           = srcu_torture_call,
 608         .cb_barrier     = srcu_torture_barrier,
 609         .stats          = srcu_torture_stats,
 610         .irq_capable    = 1,
 611         .name           = "srcu"
 612 };
 613
 614 static void srcu_torture_init(void)
 615 {
 616         rcu_sync_torture_init();
 617         WARN_ON(init_srcu_struct(&srcu_ctld));
 618         srcu_ctlp = &srcu_ctld;
 619 }
 620
 621 static void srcu_torture_cleanup(void)
 622 {
 623         cleanup_srcu_struct(&srcu_ctld);
 624         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 625 }
 626
 627 /* As above, but dynamically allocated. */
 628 static struct rcu_torture_ops srcud_ops = {
 629         .ttype          = SRCU_FLAVOR,
 630         .init           = srcu_torture_init,
 631         .cleanup        = srcu_torture_cleanup,
 632         .readlock       = srcu_torture_read_lock,
 633         .read_delay     = srcu_read_delay,
 634         .readunlock     = srcu_torture_read_unlock,
 635         .get_gp_seq     = srcu_torture_completed,
 636         .deferred_free  = srcu_torture_deferred_free,
 637         .sync           = srcu_torture_synchronize,
 638         .exp_sync       = srcu_torture_synchronize_expedited,
 639         .call           = srcu_torture_call,
 640         .cb_barrier     = srcu_torture_barrier,
 641         .stats          = srcu_torture_stats,
 642         .irq_capable    = 1,
 643         .name           = "srcud"
 644 };
 645
 646 /* As above, but broken due to inappropriate reader extension. */
 647 static struct rcu_torture_ops busted_srcud_ops = {
 648         .ttype          = SRCU_FLAVOR,
 649         .init           = srcu_torture_init,
 650         .cleanup        = srcu_torture_cleanup,
 651         .readlock       = srcu_torture_read_lock,
 652         .read_delay     = rcu_read_delay,
 653         .readunlock     = srcu_torture_read_unlock,
 654         .get_gp_seq     = srcu_torture_completed,
 655         .deferred_free  = srcu_torture_deferred_free,
 656         .sync           = srcu_torture_synchronize,
 657         .exp_sync       = srcu_torture_synchronize_expedited,
 658         .call           = srcu_torture_call,
 659         .cb_barrier     = srcu_torture_barrier,
 660         .stats          = srcu_torture_stats,
 661         .irq_capable    = 1,
 662         .extendables    = RCUTORTURE_MAX_EXTEND,
 663         .name           = "busted_srcud"
 664 };
 665
 666 /*
 667  * Definitions for RCU-tasks torture testing.
 668  */
 669
 670 static int tasks_torture_read_lock(void)
 671 {
 672         return 0;
 673 }
 674
 675 static void tasks_torture_read_unlock(int idx)
 676 {
 677 }
 678
 679 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 680 {
 681         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 682 }
 683
 684 static void synchronize_rcu_mult_test(void)
 685 {
 686         synchronize_rcu_mult(call_rcu_tasks, call_rcu);
 687 }
 688
 689 static struct rcu_torture_ops tasks_ops = {
 690         .ttype          = RCU_TASKS_FLAVOR,
 691         .init           = rcu_sync_torture_init,
 692         .readlock       = tasks_torture_read_lock,
 693         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 694         .readunlock     = tasks_torture_read_unlock,
 695         .get_gp_seq     = rcu_no_completed,
 696         .deferred_free  = rcu_tasks_torture_deferred_free,
 697         .sync           = synchronize_rcu_tasks,
 698         .exp_sync       = synchronize_rcu_mult_test,
 699         .call           = call_rcu_tasks,
 700         .cb_barrier     = rcu_barrier_tasks,
 701         .fqs            = NULL,
 702         .stats          = NULL,
 703         .irq_capable    = 1,
 704         .slow_gps       = 1,
 705         .name           = "tasks"
 706 };
 707
 708 /*
 709  * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
 710  * This implementation does not necessarily work well with CPU hotplug.
 711  */
 712
 713 static void synchronize_rcu_trivial(void)
 714 {
 715         int cpu;
 716
 717         for_each_online_cpu(cpu) {
 718                 rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
 719                 WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 720         }
 721 }
 722
 723 static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
 724 {
 725         preempt_disable();
 726         return 0;
 727 }
 728
 729 static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
 730 {
 731         preempt_enable();
 732 }
 733
 734 static struct rcu_torture_ops trivial_ops = {
 735         .ttype          = RCU_TRIVIAL_FLAVOR,
 736         .init           = rcu_sync_torture_init,
 737         .readlock       = rcu_torture_read_lock_trivial,
 738         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 739         .readunlock     = rcu_torture_read_unlock_trivial,
 740         .get_gp_seq     = rcu_no_completed,
 741         .sync           = synchronize_rcu_trivial,
 742         .exp_sync       = synchronize_rcu_trivial,
 743         .fqs            = NULL,
 744         .stats          = NULL,
 745         .irq_capable    = 1,
 746         .name           = "trivial"
 747 };
 748
 749 /*
 750  * Definitions for rude RCU-tasks torture testing.
 751  */
 752
 753 static void rcu_tasks_rude_torture_deferred_free(struct rcu_torture *p)
 754 {
 755         call_rcu_tasks_rude(&p->rtort_rcu, rcu_torture_cb);
 756 }
 757
 758 static struct rcu_torture_ops tasks_rude_ops = {
 759         .ttype          = RCU_TASKS_RUDE_FLAVOR,
 760         .init           = rcu_sync_torture_init,
 761         .readlock       = rcu_torture_read_lock_trivial,
 762         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 763         .readunlock     = rcu_torture_read_unlock_trivial,
 764         .get_gp_seq     = rcu_no_completed,
 765         .deferred_free  = rcu_tasks_rude_torture_deferred_free,
 766         .sync           = synchronize_rcu_tasks_rude,
 767         .exp_sync       = synchronize_rcu_tasks_rude,
 768         .call           = call_rcu_tasks_rude,
 769         .cb_barrier     = rcu_barrier_tasks_rude,
 770         .fqs            = NULL,
 771         .stats          = NULL,
 772         .irq_capable    = 1,
 773         .name           = "tasks-rude"
 774 };
 775
 776 /*
 777  * Definitions for tracing RCU-tasks torture testing.
 778  */
 779
 780 static int tasks_tracing_torture_read_lock(void)
 781 {
 782         rcu_read_lock_trace();
 783         return 0;
 784 }
 785
 786 static void tasks_tracing_torture_read_unlock(int idx)
 787 {
 788         rcu_read_unlock_trace();
 789 }
 790
 791 static void rcu_tasks_tracing_torture_deferred_free(struct rcu_torture *p)
 792 {
 793         call_rcu_tasks_trace(&p->rtort_rcu, rcu_torture_cb);
 794 }
 795
 796 static struct rcu_torture_ops tasks_tracing_ops = {
 797         .ttype          = RCU_TASKS_TRACING_FLAVOR,
 798         .init           = rcu_sync_torture_init,
 799         .readlock       = tasks_tracing_torture_read_lock,
 800         .read_delay     = srcu_read_delay,  /* just reuse srcu's version. */
 801         .readunlock     = tasks_tracing_torture_read_unlock,
 802         .get_gp_seq     = rcu_no_completed,
 803         .deferred_free  = rcu_tasks_tracing_torture_deferred_free,
 804         .sync           = synchronize_rcu_tasks_trace,
 805         .exp_sync       = synchronize_rcu_tasks_trace,
 806         .call           = call_rcu_tasks_trace,
 807         .cb_barrier     = rcu_barrier_tasks_trace,
 808         .fqs            = NULL,
 809         .stats          = NULL,
 810         .irq_capable    = 1,
 811         .slow_gps       = 1,
 812         .name           = "tasks-tracing"
 813 };
 814
 815 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 816 {
 817         if (!cur_ops->gp_diff)
 818                 return new - old;
 819         return cur_ops->gp_diff(new, old);
 820 }
 821
 822 static bool __maybe_unused torturing_tasks(void)
 823 {
 824         return cur_ops == &tasks_ops || cur_ops == &tasks_rude_ops;
 825 }
 826
 827 /*
 828  * RCU torture priority-boost testing.  Runs one real-time thread per
 829  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 830  * spinning waiting for them to be invoked.  If a given callback takes
 831  * too long to be invoked, we assume that priority inversion has occurred.
 832  */
 833
 834 struct rcu_boost_inflight {
 835         struct rcu_head rcu;
 836         int inflight;
 837 };
 838
 839 static void rcu_torture_boost_cb(struct rcu_head *head)
 840 {
 841         struct rcu_boost_inflight *rbip =
 842                 container_of(head, struct rcu_boost_inflight, rcu);
 843
 844         /* Ensure RCU-core accesses precede clearing ->inflight */
 845         smp_store_release(&rbip->inflight, 0);
 846 }
 847
 848 static int old_rt_runtime = -1;
 849
 850 static void rcu_torture_disable_rt_throttle(void)
 851 {
 852         /*
 853          * Disable RT throttling so that rcutorture's boost threads don't get
 854          * throttled. Only possible if rcutorture is built-in otherwise the
 855          * user should manually do this by setting the sched_rt_period_us and
 856          * sched_rt_runtime sysctls.
 857          */
 858         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
 859                 return;
 860
 861         old_rt_runtime = sysctl_sched_rt_runtime;
 862         sysctl_sched_rt_runtime = -1;
 863 }
 864
 865 static void rcu_torture_enable_rt_throttle(void)
 866 {
 867         if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
 868                 return;
 869
 870         sysctl_sched_rt_runtime = old_rt_runtime;
 871         old_rt_runtime = -1;
 872 }
 873
 874 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
 875 {
 876         if (end - start > test_boost_duration * HZ - HZ / 2) {
 877                 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 878                 n_rcu_torture_boost_failure++;
 879
 880                 return true; /* failed */
 881         }
 882
 883         return false; /* passed */
 884 }
 885
 886 static int rcu_torture_boost(void *arg)
 887 {
 888         unsigned long call_rcu_time;
 889         unsigned long endtime;
 890         unsigned long oldstarttime;
 891         struct rcu_boost_inflight rbi = { .inflight = 0 };
 892         struct sched_param sp;
 893
 894         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 895
 896         /* Set real-time priority. */
 897         sp.sched_priority = 1;
 898         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 899                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 900                 n_rcu_torture_boost_rterror++;
 901         }
 902
 903         init_rcu_head_on_stack(&rbi.rcu);
 904         /* Each pass through the following loop does one boost-test cycle. */
 905         do {
 906                 /* Track if the test failed already in this test interval? */
 907                 bool failed = false;
 908
 909                 /* Increment n_rcu_torture_boosts once per boost-test */
 910                 while (!kthread_should_stop()) {
 911                         if (mutex_trylock(&boost_mutex)) {
 912                                 n_rcu_torture_boosts++;
 913                                 mutex_unlock(&boost_mutex);
 914                                 break;
 915                         }
 916                         schedule_timeout_uninterruptible(1);
 917                 }
 918                 if (kthread_should_stop())
 919                         goto checkwait;
 920
 921                 /* Wait for the next test interval. */
 922                 oldstarttime = boost_starttime;
 923                 while (time_before(jiffies, oldstarttime)) {
 924                         schedule_timeout_interruptible(oldstarttime - jiffies);
 925                         stutter_wait("rcu_torture_boost");
 926                         if (torture_must_stop())
 927                                 goto checkwait;
 928                 }
 929
 930                 /* Do one boost-test interval. */
 931                 endtime = oldstarttime + test_boost_duration * HZ;
 932                 call_rcu_time = jiffies;
 933                 while (time_before(jiffies, endtime)) {
 934                         /* If we don't have a callback in flight, post one. */
 935                         if (!smp_load_acquire(&rbi.inflight)) {
 936                                 /* RCU core before ->inflight = 1. */
 937                                 smp_store_release(&rbi.inflight, 1);
 938                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 939                                 /* Check if the boost test failed */
 940                                 failed = failed ||
 941                                          rcu_torture_boost_failed(call_rcu_time,
 942                                                                  jiffies);
 943                                 call_rcu_time = jiffies;
 944                         }
 945                         stutter_wait("rcu_torture_boost");
 946                         if (torture_must_stop())
 947                                 goto checkwait;
 948                 }
 949
 950                 /*
 951                  * If boost never happened, then inflight will always be 1, in
 952                  * this case the boost check would never happen in the above
 953                  * loop so do another one here.
 954                  */
 955                 if (!failed && smp_load_acquire(&rbi.inflight))
 956                         rcu_torture_boost_failed(call_rcu_time, jiffies);
 957
 958                 /*
 959                  * Set the start time of the next test interval.
 960                  * Yes, this is vulnerable to long delays, but such
 961                  * delays simply cause a false negative for the next
 962                  * interval.  Besides, we are running at RT priority,
 963                  * so delays should be relatively rare.
 964                  */
 965                 while (oldstarttime == boost_starttime &&
 966                        !kthread_should_stop()) {
 967                         if (mutex_trylock(&boost_mutex)) {
 968                                 boost_starttime = jiffies +
 969                                                   test_boost_interval * HZ;
 970                                 mutex_unlock(&boost_mutex);
 971                                 break;
 972                         }
 973                         schedule_timeout_uninterruptible(1);
 974                 }
 975
 976                 /* Go do the stutter. */
 977 checkwait:      stutter_wait("rcu_torture_boost");
 978         } while (!torture_must_stop());
 979
 980         /* Clean up and exit. */
 981         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 982                 torture_shutdown_absorb("rcu_torture_boost");
 983                 schedule_timeout_uninterruptible(1);
 984         }
 985         destroy_rcu_head_on_stack(&rbi.rcu);
 986         torture_kthread_stopping("rcu_torture_boost");
 987         return 0;
 988 }
 989
 990 /*
 991  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 992  * bursts of calls to force_quiescent_state(), increasing the probability
 993  * of occurrence of some important types of race conditions.
 994  */
 995 static int
 996 rcu_torture_fqs(void *arg)
 997 {
 998         unsigned long fqs_resume_time;
 999         int fqs_burst_remaining;
1000
1001         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
1002         do {
1003                 fqs_resume_time = jiffies + fqs_stutter * HZ;
1004                 while (time_before(jiffies, fqs_resume_time) &&
1005                        !kthread_should_stop()) {
1006                         schedule_timeout_interruptible(1);
1007                 }
1008                 fqs_burst_remaining = fqs_duration;
1009                 while (fqs_burst_remaining > 0 &&
1010                        !kthread_should_stop()) {
1011                         cur_ops->fqs();
1012                         udelay(fqs_holdoff);
1013                         fqs_burst_remaining -= fqs_holdoff;
1014                 }
1015                 stutter_wait("rcu_torture_fqs");
1016         } while (!torture_must_stop());
1017         torture_kthread_stopping("rcu_torture_fqs");
1018         return 0;
1019 }
1020
1021 /*
1022  * RCU torture writer kthread.  Repeatedly substitutes a new structure
1023  * for that pointed to by rcu_torture_current, freeing the old structure
1024  * after a series of grace periods (the "pipeline").
1025  */
1026 static int
1027 rcu_torture_writer(void *arg)
1028 {
1029         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
1030         int expediting = 0;
1031         unsigned long gp_snap;
1032         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
1033         bool gp_sync1 = gp_sync;
1034         int i;
1035         struct rcu_torture *rp;
1036         struct rcu_torture *old_rp;
1037         static DEFINE_TORTURE_RANDOM(rand);
1038         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
1039                            RTWS_COND_GET, RTWS_SYNC };
1040         int nsynctypes = 0;
1041
1042         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
1043         if (!can_expedite)
1044                 pr_alert("%s" TORTURE_FLAG
1045                          " GP expediting controlled from boot/sysfs for %s.\n",
1046                          torture_type, cur_ops->name);
1047
1048         /* Initialize synctype[] array.  If none set, take default. */
1049         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
1050                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
1051         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
1052                 synctype[nsynctypes++] = RTWS_COND_GET;
1053                 pr_info("%s: Testing conditional GPs.\n", __func__);
1054         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
1055                 pr_alert("%s: gp_cond without primitives.\n", __func__);
1056         }
1057         if (gp_exp1 && cur_ops->exp_sync) {
1058                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
1059                 pr_info("%s: Testing expedited GPs.\n", __func__);
1060         } else if (gp_exp && !cur_ops->exp_sync) {
1061                 pr_alert("%s: gp_exp without primitives.\n", __func__);
1062         }
1063         if (gp_normal1 && cur_ops->deferred_free) {
1064                 synctype[nsynctypes++] = RTWS_DEF_FREE;
1065                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
1066         } else if (gp_normal && !cur_ops->deferred_free) {
1067                 pr_alert("%s: gp_normal without primitives.\n", __func__);
1068         }
1069         if (gp_sync1 && cur_ops->sync) {
1070                 synctype[nsynctypes++] = RTWS_SYNC;
1071                 pr_info("%s: Testing normal GPs.\n", __func__);
1072         } else if (gp_sync && !cur_ops->sync) {
1073                 pr_alert("%s: gp_sync without primitives.\n", __func__);
1074         }
1075         if (WARN_ONCE(nsynctypes == 0,
1076                       "rcu_torture_writer: No update-side primitives.\n")) {
1077                 /*
1078                  * No updates primitives, so don't try updating.
1079                  * The resulting test won't be testing much, hence the
1080                  * above WARN_ONCE().
1081                  */
1082                 rcu_torture_writer_state = RTWS_STOPPING;
1083                 torture_kthread_stopping("rcu_torture_writer");
1084         }
1085
1086         do {
1087                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
1088                 schedule_timeout_uninterruptible(1);
1089                 rp = rcu_torture_alloc();
1090                 if (rp == NULL)
1091                         continue;
1092                 rp->rtort_pipe_count = 0;
1093                 rcu_torture_writer_state = RTWS_DELAY;
1094                 udelay(torture_random(&rand) & 0x3ff);
1095                 rcu_torture_writer_state = RTWS_REPLACE;
1096                 old_rp = rcu_dereference_check(rcu_torture_current,
1097                                                current == writer_task);
1098                 rp->rtort_mbtest = 1;
1099                 rcu_assign_pointer(rcu_torture_current, rp);
1100                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1101                 if (old_rp) {
1102                         i = old_rp->rtort_pipe_count;
1103                         if (i > RCU_TORTURE_PIPE_LEN)
1104                                 i = RCU_TORTURE_PIPE_LEN;
1105                         atomic_inc(&rcu_torture_wcount[i]);
1106                         WRITE_ONCE(old_rp->rtort_pipe_count,
1107                                    old_rp->rtort_pipe_count + 1);
1108                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1109                         case RTWS_DEF_FREE:
1110                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1111                                 cur_ops->deferred_free(old_rp);
1112                                 break;
1113                         case RTWS_EXP_SYNC:
1114                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1115                                 cur_ops->exp_sync();
1116                                 rcu_torture_pipe_update(old_rp);
1117                                 break;
1118                         case RTWS_COND_GET:
1119                                 rcu_torture_writer_state = RTWS_COND_GET;
1120                                 gp_snap = cur_ops->get_state();
1121                                 i = torture_random(&rand) % 16;
1122                                 if (i != 0)
1123                                         schedule_timeout_interruptible(i);
1124                                 udelay(torture_random(&rand) % 1000);
1125                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1126                                 cur_ops->cond_sync(gp_snap);
1127                                 rcu_torture_pipe_update(old_rp);
1128                                 break;
1129                         case RTWS_SYNC:
1130                                 rcu_torture_writer_state = RTWS_SYNC;
1131                                 cur_ops->sync();
1132                                 rcu_torture_pipe_update(old_rp);
1133                                 break;
1134                         default:
1135                                 WARN_ON_ONCE(1);
1136                                 break;
1137                         }
1138                 }
1139                 WRITE_ONCE(rcu_torture_current_version,
1140                            rcu_torture_current_version + 1);
1141                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1142                 if (can_expedite &&
1143                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1144                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1145                         if (expediting >= 0)
1146                                 rcu_expedite_gp();
1147                         else
1148                                 rcu_unexpedite_gp();
1149                         if (++expediting > 3)
1150                                 expediting = -expediting;
1151                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1152                         can_expedite = !rcu_gp_is_expedited() &&
1153                                        !rcu_gp_is_normal();
1154                 }
1155                 rcu_torture_writer_state = RTWS_STUTTER;
1156                 if (stutter_wait("rcu_torture_writer") &&
1157                     !READ_ONCE(rcu_fwd_cb_nodelay) &&
1158                     !cur_ops->slow_gps &&
1159                     !torture_must_stop() &&
1160                     rcu_inkernel_boot_has_ended())
1161                         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1162                                 if (list_empty(&rcu_tortures[i].rtort_free) &&
1163                                     rcu_access_pointer(rcu_torture_current) !=
1164                                     &rcu_tortures[i]) {
1165                                         rcu_ftrace_dump(DUMP_ALL);
1166                                         WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
1167                                 }
1168         } while (!torture_must_stop());
1169         /* Reset expediting back to unexpedited. */
1170         if (expediting > 0)
1171                 expediting = -expediting;
1172         while (can_expedite && expediting++ < 0)
1173                 rcu_unexpedite_gp();
1174         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1175         if (!can_expedite)
1176                 pr_alert("%s" TORTURE_FLAG
1177                          " Dynamic grace-period expediting was disabled.\n",
1178                          torture_type);
1179         rcu_torture_writer_state = RTWS_STOPPING;
1180         torture_kthread_stopping("rcu_torture_writer");
1181         return 0;
1182 }
1183
1184 /*
1185  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1186  * delay between calls.
1187  */
1188 static int
1189 rcu_torture_fakewriter(void *arg)
1190 {
1191         DEFINE_TORTURE_RANDOM(rand);
1192
1193         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1194         set_user_nice(current, MAX_NICE);
1195
1196         do {
1197                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1198                 udelay(torture_random(&rand) & 0x3ff);
1199                 if (cur_ops->cb_barrier != NULL &&
1200                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1201                         cur_ops->cb_barrier();
1202                 } else if (gp_normal == gp_exp) {
1203                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1204                                 cur_ops->sync();
1205                         else if (cur_ops->exp_sync)
1206                                 cur_ops->exp_sync();
1207                 } else if (gp_normal && cur_ops->sync) {
1208                         cur_ops->sync();
1209                 } else if (cur_ops->exp_sync) {
1210                         cur_ops->exp_sync();
1211                 }
1212                 stutter_wait("rcu_torture_fakewriter");
1213         } while (!torture_must_stop());
1214
1215         torture_kthread_stopping("rcu_torture_fakewriter");
1216         return 0;
1217 }
1218
1219 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1220 {
1221         kfree(rhp);
1222 }
1223
1224 /*
1225  * Do one extension of an RCU read-side critical section using the
1226  * current reader state in readstate (set to zero for initial entry
1227  * to extended critical section), set the new state as specified by
1228  * newstate (set to zero for final exit from extended critical section),
1229  * and random-number-generator state in trsp.  If this is neither the
1230  * beginning or end of the critical section and if there was actually a
1231  * change, do a ->read_delay().
1232  */
1233 static void rcutorture_one_extend(int *readstate, int newstate,
1234                                   struct torture_random_state *trsp,
1235                                   struct rt_read_seg *rtrsp)
1236 {
1237         unsigned long flags;
1238         int idxnew = -1;
1239         int idxold = *readstate;
1240         int statesnew = ~*readstate & newstate;
1241         int statesold = *readstate & ~newstate;
1242
1243         WARN_ON_ONCE(idxold < 0);
1244         WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1245         rtrsp->rt_readstate = newstate;
1246
1247         /* First, put new protection in place to avoid critical-section gap. */
1248         if (statesnew & RCUTORTURE_RDR_BH)
1249                 local_bh_disable();
1250         if (statesnew & RCUTORTURE_RDR_IRQ)
1251                 local_irq_disable();
1252         if (statesnew & RCUTORTURE_RDR_PREEMPT)
1253                 preempt_disable();
1254         if (statesnew & RCUTORTURE_RDR_RBH)
1255                 rcu_read_lock_bh();
1256         if (statesnew & RCUTORTURE_RDR_SCHED)
1257                 rcu_read_lock_sched();
1258         if (statesnew & RCUTORTURE_RDR_RCU)
1259                 idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1260
1261         /* Next, remove old protection, irq first due to bh conflict. */
1262         if (statesold & RCUTORTURE_RDR_IRQ)
1263                 local_irq_enable();
1264         if (statesold & RCUTORTURE_RDR_BH)
1265                 local_bh_enable();
1266         if (statesold & RCUTORTURE_RDR_PREEMPT)
1267                 preempt_enable();
1268         if (statesold & RCUTORTURE_RDR_RBH)
1269                 rcu_read_unlock_bh();
1270         if (statesold & RCUTORTURE_RDR_SCHED)
1271                 rcu_read_unlock_sched();
1272         if (statesold & RCUTORTURE_RDR_RCU) {
1273                 bool lockit = !statesnew && !(torture_random(trsp) & 0xffff);
1274
1275                 if (lockit)
1276                         raw_spin_lock_irqsave(&current->pi_lock, flags);
1277                 cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1278                 if (lockit)
1279                         raw_spin_unlock_irqrestore(&current->pi_lock, flags);
1280         }
1281
1282         /* Delay if neither beginning nor end and there was a change. */
1283         if ((statesnew || statesold) && *readstate && newstate)
1284                 cur_ops->read_delay(trsp, rtrsp);
1285
1286         /* Update the reader state. */
1287         if (idxnew == -1)
1288                 idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1289         WARN_ON_ONCE(idxnew < 0);
1290         WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1291         *readstate = idxnew | newstate;
1292         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1293         WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1294 }
1295
1296 /* Return the biggest extendables mask given current RCU and boot parameters. */
1297 static int rcutorture_extend_mask_max(void)
1298 {
1299         int mask;
1300
1301         WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1302         mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1303         mask = mask | RCUTORTURE_RDR_RCU;
1304         return mask;
1305 }
1306
1307 /* Return a random protection state mask, but with at least one bit set. */
1308 static int
1309 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1310 {
1311         int mask = rcutorture_extend_mask_max();
1312         unsigned long randmask1 = torture_random(trsp) >> 8;
1313         unsigned long randmask2 = randmask1 >> 3;
1314
1315         WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1316         /* Mostly only one bit (need preemption!), sometimes lots of bits. */
1317         if (!(randmask1 & 0x7))
1318                 mask = mask & randmask2;
1319         else
1320                 mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1321         /* Can't enable bh w/irq disabled. */
1322         if ((mask & RCUTORTURE_RDR_IRQ) &&
1323             ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1324              (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1325                 mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1326         return mask ?: RCUTORTURE_RDR_RCU;
1327 }
1328
1329 /*
1330  * Do a randomly selected number of extensions of an existing RCU read-side
1331  * critical section.
1332  */
1333 static struct rt_read_seg *
1334 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1335                        struct rt_read_seg *rtrsp)
1336 {
1337         int i;
1338         int j;
1339         int mask = rcutorture_extend_mask_max();
1340
1341         WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1342         if (!((mask - 1) & mask))
1343                 return rtrsp;  /* Current RCU reader not extendable. */
1344         /* Bias towards larger numbers of loops. */
1345         i = (torture_random(trsp) >> 3);
1346         i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1347         for (j = 0; j < i; j++) {
1348                 mask = rcutorture_extend_mask(*readstate, trsp);
1349                 rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1350         }
1351         return &rtrsp[j];
1352 }
1353
1354 /*
1355  * Do one read-side critical section, returning false if there was
1356  * no data to read.  Can be invoked both from process context and
1357  * from a timer handler.
1358  */
1359 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1360 {
1361         int i;
1362         unsigned long started;
1363         unsigned long completed;
1364         int newstate;
1365         struct rcu_torture *p;
1366         int pipe_count;
1367         int readstate = 0;
1368         struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1369         struct rt_read_seg *rtrsp = &rtseg[0];
1370         struct rt_read_seg *rtrsp1;
1371         unsigned long long ts;
1372
1373         newstate = rcutorture_extend_mask(readstate, trsp);
1374         rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1375         started = cur_ops->get_gp_seq();
1376         ts = rcu_trace_clock_local();
1377         p = rcu_dereference_check(rcu_torture_current,
1378                                   rcu_read_lock_bh_held() ||
1379                                   rcu_read_lock_sched_held() ||
1380                                   srcu_read_lock_held(srcu_ctlp) ||
1381                                   rcu_read_lock_trace_held() ||
1382                                   torturing_tasks());
1383         if (p == NULL) {
1384                 /* Wait for rcu_torture_writer to get underway */
1385                 rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1386                 return false;
1387         }
1388         if (p->rtort_mbtest == 0)
1389                 atomic_inc(&n_rcu_torture_mberror);
1390         rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1391         preempt_disable();
1392         pipe_count = READ_ONCE(p->rtort_pipe_count);
1393         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1394                 /* Should not happen, but... */
1395                 pipe_count = RCU_TORTURE_PIPE_LEN;
1396         }
1397         completed = cur_ops->get_gp_seq();
1398         if (pipe_count > 1) {
1399                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1400                                           ts, started, completed);
1401                 rcu_ftrace_dump(DUMP_ALL);
1402         }
1403         __this_cpu_inc(rcu_torture_count[pipe_count]);
1404         completed = rcutorture_seq_diff(completed, started);
1405         if (completed > RCU_TORTURE_PIPE_LEN) {
1406                 /* Should not happen, but... */
1407                 completed = RCU_TORTURE_PIPE_LEN;
1408         }
1409         __this_cpu_inc(rcu_torture_batch[completed]);
1410         preempt_enable();
1411         rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1412         WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1413
1414         /* If error or close call, record the sequence of reader protections. */
1415         if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1416                 i = 0;
1417                 for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1418                         err_segs[i++] = *rtrsp1;
1419                 rt_read_nsegs = i;
1420         }
1421
1422         return true;
1423 }
1424
1425 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1426
1427 /*
1428  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1429  * incrementing the corresponding element of the pipeline array.  The
1430  * counter in the element should never be greater than 1, otherwise, the
1431  * RCU implementation is broken.
1432  */
1433 static void rcu_torture_timer(struct timer_list *unused)
1434 {
1435         atomic_long_inc(&n_rcu_torture_timers);
1436         (void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1437
1438         /* Test call_rcu() invocation from interrupt handler. */
1439         if (cur_ops->call) {
1440                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1441
1442                 if (rhp)
1443                         cur_ops->call(rhp, rcu_torture_timer_cb);
1444         }
1445 }
1446
1447 /*
1448  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1449  * incrementing the corresponding element of the pipeline array.  The
1450  * counter in the element should never be greater than 1, otherwise, the
1451  * RCU implementation is broken.
1452  */
1453 static int
1454 rcu_torture_reader(void *arg)
1455 {
1456         unsigned long lastsleep = jiffies;
1457         long myid = (long)arg;
1458         int mynumonline = myid;
1459         DEFINE_TORTURE_RANDOM(rand);
1460         struct timer_list t;
1461
1462         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1463         set_user_nice(current, MAX_NICE);
1464         if (irqreader && cur_ops->irq_capable)
1465                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1466         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
1467         do {
1468                 if (irqreader && cur_ops->irq_capable) {
1469                         if (!timer_pending(&t))
1470                                 mod_timer(&t, jiffies + 1);
1471                 }
1472                 if (!rcu_torture_one_read(&rand) && !torture_must_stop())
1473                         schedule_timeout_interruptible(HZ);
1474                 if (time_after(jiffies, lastsleep) && !torture_must_stop()) {
1475                         schedule_timeout_interruptible(1);
1476                         lastsleep = jiffies + 10;
1477                 }
1478                 while (num_online_cpus() < mynumonline && !torture_must_stop())
1479                         schedule_timeout_interruptible(HZ / 5);
1480                 stutter_wait("rcu_torture_reader");
1481         } while (!torture_must_stop());
1482         if (irqreader && cur_ops->irq_capable) {
1483                 del_timer_sync(&t);
1484                 destroy_timer_on_stack(&t);
1485         }
1486         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
1487         torture_kthread_stopping("rcu_torture_reader");
1488         return 0;
1489 }
1490
1491 /*
1492  * Print torture statistics.  Caller must ensure that there is only
1493  * one call to this function at a given time!!!  This is normally
1494  * accomplished by relying on the module system to only have one copy
1495  * of the module loaded, and then by giving the rcu_torture_stats
1496  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1497  * thread is not running).
1498  */
1499 static void
1500 rcu_torture_stats_print(void)
1501 {
1502         int cpu;
1503         int i;
1504         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1505         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1506         struct rcu_torture *rtcp;
1507         static unsigned long rtcv_snap = ULONG_MAX;
1508         static bool splatted;
1509         struct task_struct *wtp;
1510
1511         for_each_possible_cpu(cpu) {
1512                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1513                         pipesummary[i] += READ_ONCE(per_cpu(rcu_torture_count, cpu)[i]);
1514                         batchsummary[i] += READ_ONCE(per_cpu(rcu_torture_batch, cpu)[i]);
1515                 }
1516         }
1517         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1518                 if (pipesummary[i] != 0)
1519                         break;
1520         }
1521
1522         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1523         rtcp = rcu_access_pointer(rcu_torture_current);
1524         pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1525                 rtcp,
1526                 rtcp && !rcu_stall_is_suppressed_at_boot() ? "ver" : "VER",
1527                 rcu_torture_current_version,
1528                 list_empty(&rcu_torture_freelist),
1529                 atomic_read(&n_rcu_torture_alloc),
1530                 atomic_read(&n_rcu_torture_alloc_fail),
1531                 atomic_read(&n_rcu_torture_free));
1532         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1533                 atomic_read(&n_rcu_torture_mberror),
1534                 n_rcu_torture_barrier_error,
1535                 n_rcu_torture_boost_ktrerror,
1536                 n_rcu_torture_boost_rterror);
1537         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1538                 n_rcu_torture_boost_failure,
1539                 n_rcu_torture_boosts,
1540                 atomic_long_read(&n_rcu_torture_timers));
1541         torture_onoff_stats();
1542         pr_cont("barrier: %ld/%ld:%ld\n",
1543                 data_race(n_barrier_successes),
1544                 data_race(n_barrier_attempts),
1545                 data_race(n_rcu_torture_barrier_error));
1546
1547         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1548         if (atomic_read(&n_rcu_torture_mberror) ||
1549             n_rcu_torture_barrier_error || n_rcu_torture_boost_ktrerror ||
1550             n_rcu_torture_boost_rterror || n_rcu_torture_boost_failure ||
1551             i > 1) {
1552                 pr_cont("%s", "!!! ");
1553                 atomic_inc(&n_rcu_torture_error);
1554                 WARN_ON_ONCE(atomic_read(&n_rcu_torture_mberror));
1555                 WARN_ON_ONCE(n_rcu_torture_barrier_error);  // rcu_barrier()
1556                 WARN_ON_ONCE(n_rcu_torture_boost_ktrerror); // no boost kthread
1557                 WARN_ON_ONCE(n_rcu_torture_boost_rterror); // can't set RT prio
1558                 WARN_ON_ONCE(n_rcu_torture_boost_failure); // RCU boost failed
1559                 WARN_ON_ONCE(i > 1); // Too-short grace period
1560         }
1561         pr_cont("Reader Pipe: ");
1562         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1563                 pr_cont(" %ld", pipesummary[i]);
1564         pr_cont("\n");
1565
1566         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1567         pr_cont("Reader Batch: ");
1568         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1569                 pr_cont(" %ld", batchsummary[i]);
1570         pr_cont("\n");
1571
1572         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1573         pr_cont("Free-Block Circulation: ");
1574         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1575                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1576         }
1577         pr_cont("\n");
1578
1579         if (cur_ops->stats)
1580                 cur_ops->stats();
1581         if (rtcv_snap == rcu_torture_current_version &&
1582             rcu_access_pointer(rcu_torture_current) &&
1583             !rcu_stall_is_suppressed()) {
1584                 int __maybe_unused flags = 0;
1585                 unsigned long __maybe_unused gp_seq = 0;
1586
1587                 rcutorture_get_gp_data(cur_ops->ttype,
1588                                        &flags, &gp_seq);
1589                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1590                                         &flags, &gp_seq);
1591                 wtp = READ_ONCE(writer_task);
1592                 pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1593                          rcu_torture_writer_state_getname(),
1594                          rcu_torture_writer_state, gp_seq, flags,
1595                          wtp == NULL ? ~0UL : wtp->state,
1596                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1597                 if (!splatted && wtp) {
1598                         sched_show_task(wtp);
1599                         splatted = true;
1600                 }
1601                 show_rcu_gp_kthreads();
1602                 rcu_ftrace_dump(DUMP_ALL);
1603         }
1604         rtcv_snap = rcu_torture_current_version;
1605 }
1606
1607 /*
1608  * Periodically prints torture statistics, if periodic statistics printing
1609  * was specified via the stat_interval module parameter.
1610  */
1611 static int
1612 rcu_torture_stats(void *arg)
1613 {
1614         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1615         do {
1616                 schedule_timeout_interruptible(stat_interval * HZ);
1617                 rcu_torture_stats_print();
1618                 torture_shutdown_absorb("rcu_torture_stats");
1619         } while (!torture_must_stop());
1620         torture_kthread_stopping("rcu_torture_stats");
1621         return 0;
1622 }
1623
1624 static void
1625 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1626 {
1627         pr_alert("%s" TORTURE_FLAG
1628                  "--- %s: nreaders=%d nfakewriters=%d "
1629                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1630                  "shuffle_interval=%d stutter=%d irqreader=%d "
1631                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1632                  "test_boost=%d/%d test_boost_interval=%d "
1633                  "test_boost_duration=%d shutdown_secs=%d "
1634                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1635                  "stall_cpu_block=%d "
1636                  "n_barrier_cbs=%d "
1637                  "onoff_interval=%d onoff_holdoff=%d\n",
1638                  torture_type, tag, nrealreaders, nfakewriters,
1639                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1640                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1641                  test_boost, cur_ops->can_boost,
1642                  test_boost_interval, test_boost_duration, shutdown_secs,
1643                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1644                  stall_cpu_block,
1645                  n_barrier_cbs,
1646                  onoff_interval, onoff_holdoff);
1647 }
1648
1649 static int rcutorture_booster_cleanup(unsigned int cpu)
1650 {
1651         struct task_struct *t;
1652
1653         if (boost_tasks[cpu] == NULL)
1654                 return 0;
1655         mutex_lock(&boost_mutex);
1656         t = boost_tasks[cpu];
1657         boost_tasks[cpu] = NULL;
1658         rcu_torture_enable_rt_throttle();
1659         mutex_unlock(&boost_mutex);
1660
1661         /* This must be outside of the mutex, otherwise deadlock! */
1662         torture_stop_kthread(rcu_torture_boost, t);
1663         return 0;
1664 }
1665
1666 static int rcutorture_booster_init(unsigned int cpu)
1667 {
1668         int retval;
1669
1670         if (boost_tasks[cpu] != NULL)
1671                 return 0;  /* Already created, nothing more to do. */
1672
1673         /* Don't allow time recalculation while creating a new task. */
1674         mutex_lock(&boost_mutex);
1675         rcu_torture_disable_rt_throttle();
1676         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1677         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1678                                                   cpu_to_node(cpu),
1679                                                   "rcu_torture_boost");
1680         if (IS_ERR(boost_tasks[cpu])) {
1681                 retval = PTR_ERR(boost_tasks[cpu]);
1682                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1683                 n_rcu_torture_boost_ktrerror++;
1684                 boost_tasks[cpu] = NULL;
1685                 mutex_unlock(&boost_mutex);
1686                 return retval;
1687         }
1688         kthread_bind(boost_tasks[cpu], cpu);
1689         wake_up_process(boost_tasks[cpu]);
1690         mutex_unlock(&boost_mutex);
1691         return 0;
1692 }
1693
1694 /*
1695  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1696  * induces a CPU stall for the time specified by stall_cpu.
1697  */
1698 static int rcu_torture_stall(void *args)
1699 {
1700         int idx;
1701         unsigned long stop_at;
1702
1703         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1704         if (stall_cpu_holdoff > 0) {
1705                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1706                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1707                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1708         }
1709         if (!kthread_should_stop() && stall_gp_kthread > 0) {
1710                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin GP stall");
1711                 rcu_gp_set_torture_wait(stall_gp_kthread * HZ);
1712                 for (idx = 0; idx < stall_gp_kthread + 2; idx++) {
1713                         if (kthread_should_stop())
1714                                 break;
1715                         schedule_timeout_uninterruptible(HZ);
1716                 }
1717         }
1718         if (!kthread_should_stop() && stall_cpu > 0) {
1719                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin CPU stall");
1720                 stop_at = ktime_get_seconds() + stall_cpu;
1721                 /* RCU CPU stall is expected behavior in following code. */
1722                 idx = cur_ops->readlock();
1723                 if (stall_cpu_irqsoff)
1724                         local_irq_disable();
1725                 else if (!stall_cpu_block)
1726                         preempt_disable();
1727                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1728                          raw_smp_processor_id());
1729                 while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1730                                     stop_at))
1731                         if (stall_cpu_block)
1732                                 schedule_timeout_uninterruptible(HZ);
1733                 if (stall_cpu_irqsoff)
1734                         local_irq_enable();
1735                 else if (!stall_cpu_block)
1736                         preempt_enable();
1737                 cur_ops->readunlock(idx);
1738         }
1739         pr_alert("rcu_torture_stall end.\n");
1740         torture_shutdown_absorb("rcu_torture_stall");
1741         while (!kthread_should_stop())
1742                 schedule_timeout_interruptible(10 * HZ);
1743         return 0;
1744 }
1745
1746 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1747 static int __init rcu_torture_stall_init(void)
1748 {
1749         if (stall_cpu <= 0 && stall_gp_kthread <= 0)
1750                 return 0;
1751         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1752 }
1753
1754 /* State structure for forward-progress self-propagating RCU callback. */
1755 struct fwd_cb_state {
1756         struct rcu_head rh;
1757         int stop;
1758 };
1759
1760 /*
1761  * Forward-progress self-propagating RCU callback function.  Because
1762  * callbacks run from softirq, this function is an implicit RCU read-side
1763  * critical section.
1764  */
1765 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1766 {
1767         struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1768
1769         if (READ_ONCE(fcsp->stop)) {
1770                 WRITE_ONCE(fcsp->stop, 2);
1771                 return;
1772         }
1773         cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1774 }
1775
1776 /* State for continuous-flood RCU callbacks. */
1777 struct rcu_fwd_cb {
1778         struct rcu_head rh;
1779         struct rcu_fwd_cb *rfc_next;
1780         struct rcu_fwd *rfc_rfp;
1781         int rfc_gps;
1782 };
1783
1784 #define MAX_FWD_CB_JIFFIES      (8 * HZ) /* Maximum CB test duration. */
1785 #define MIN_FWD_CB_LAUNDERS     3       /* This many CB invocations to count. */
1786 #define MIN_FWD_CBS_LAUNDERED   100     /* Number of counted CBs. */
1787 #define FWD_CBS_HIST_DIV        10      /* Histogram buckets/second. */
1788 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1789
1790 struct rcu_launder_hist {
1791         long n_launders;
1792         unsigned long launder_gp_seq;
1793 };
1794
1795 struct rcu_fwd {
1796         spinlock_t rcu_fwd_lock;
1797         struct rcu_fwd_cb *rcu_fwd_cb_head;
1798         struct rcu_fwd_cb **rcu_fwd_cb_tail;
1799         long n_launders_cb;
1800         unsigned long rcu_fwd_startat;
1801         struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1802         unsigned long rcu_launder_gp_seq_start;
1803 };
1804
1805 static struct rcu_fwd *rcu_fwds;
1806 static bool rcu_fwd_emergency_stop;
1807
1808 static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
1809 {
1810         unsigned long gps;
1811         unsigned long gps_old;
1812         int i;
1813         int j;
1814
1815         for (i = ARRAY_SIZE(rfp->n_launders_hist) - 1; i > 0; i--)
1816                 if (rfp->n_launders_hist[i].n_launders > 0)
1817                         break;
1818         pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1819                  __func__, jiffies - rfp->rcu_fwd_startat);
1820         gps_old = rfp->rcu_launder_gp_seq_start;
1821         for (j = 0; j <= i; j++) {
1822                 gps = rfp->n_launders_hist[j].launder_gp_seq;
1823                 pr_cont(" %ds/%d: %ld:%ld",
1824                         j + 1, FWD_CBS_HIST_DIV,
1825                         rfp->n_launders_hist[j].n_launders,
1826                         rcutorture_seq_diff(gps, gps_old));
1827                 gps_old = gps;
1828         }
1829         pr_cont("\n");
1830 }
1831
1832 /* Callback function for continuous-flood RCU callbacks. */
1833 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1834 {
1835         unsigned long flags;
1836         int i;
1837         struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1838         struct rcu_fwd_cb **rfcpp;
1839         struct rcu_fwd *rfp = rfcp->rfc_rfp;
1840
1841         rfcp->rfc_next = NULL;
1842         rfcp->rfc_gps++;
1843         spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
1844         rfcpp = rfp->rcu_fwd_cb_tail;
1845         rfp->rcu_fwd_cb_tail = &rfcp->rfc_next;
1846         WRITE_ONCE(*rfcpp, rfcp);
1847         WRITE_ONCE(rfp->n_launders_cb, rfp->n_launders_cb + 1);
1848         i = ((jiffies - rfp->rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1849         if (i >= ARRAY_SIZE(rfp->n_launders_hist))
1850                 i = ARRAY_SIZE(rfp->n_launders_hist) - 1;
1851         rfp->n_launders_hist[i].n_launders++;
1852         rfp->n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1853         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1854 }
1855
1856 // Give the scheduler a chance, even on nohz_full CPUs.
1857 static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
1858 {
1859         if (IS_ENABLED(CONFIG_PREEMPTION) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
1860                 // Real call_rcu() floods hit userspace, so emulate that.
1861                 if (need_resched() || (iter & 0xfff))
1862                         schedule();
1863                 return;
1864         }
1865         // No userspace emulation: CB invocation throttles call_rcu()
1866         cond_resched();
1867 }
1868
1869 /*
1870  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1871  * test is over or because we hit an OOM event.
1872  */
1873 static unsigned long rcu_torture_fwd_prog_cbfree(struct rcu_fwd *rfp)
1874 {
1875         unsigned long flags;
1876         unsigned long freed = 0;
1877         struct rcu_fwd_cb *rfcp;
1878
1879         for (;;) {
1880                 spin_lock_irqsave(&rfp->rcu_fwd_lock, flags);
1881                 rfcp = rfp->rcu_fwd_cb_head;
1882                 if (!rfcp) {
1883                         spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1884                         break;
1885                 }
1886                 rfp->rcu_fwd_cb_head = rfcp->rfc_next;
1887                 if (!rfp->rcu_fwd_cb_head)
1888                         rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
1889                 spin_unlock_irqrestore(&rfp->rcu_fwd_lock, flags);
1890                 kfree(rfcp);
1891                 freed++;
1892                 rcu_torture_fwd_prog_cond_resched(freed);
1893                 if (tick_nohz_full_enabled()) {
1894                         local_irq_save(flags);
1895                         rcu_momentary_dyntick_idle();
1896                         local_irq_restore(flags);
1897                 }
1898         }
1899         return freed;
1900 }
1901
1902 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1903 static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
1904                                     int *tested, int *tested_tries)
1905 {
1906         unsigned long cver;
1907         unsigned long dur;
1908         struct fwd_cb_state fcs;
1909         unsigned long gps;
1910         int idx;
1911         int sd;
1912         int sd4;
1913         bool selfpropcb = false;
1914         unsigned long stopat;
1915         static DEFINE_TORTURE_RANDOM(trs);
1916
1917         if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1918                 init_rcu_head_on_stack(&fcs.rh);
1919                 selfpropcb = true;
1920         }
1921
1922         /* Tight loop containing cond_resched(). */
1923         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1924         cur_ops->sync(); /* Later readers see above write. */
1925         if  (selfpropcb) {
1926                 WRITE_ONCE(fcs.stop, 0);
1927                 cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1928         }
1929         cver = READ_ONCE(rcu_torture_current_version);
1930         gps = cur_ops->get_gp_seq();
1931         sd = cur_ops->stall_dur() + 1;
1932         sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1933         dur = sd4 + torture_random(&trs) % (sd - sd4);
1934         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
1935         stopat = rfp->rcu_fwd_startat + dur;
1936         while (time_before(jiffies, stopat) &&
1937                !shutdown_time_arrived() &&
1938                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1939                 idx = cur_ops->readlock();
1940                 udelay(10);
1941                 cur_ops->readunlock(idx);
1942                 if (!fwd_progress_need_resched || need_resched())
1943                         cond_resched();
1944         }
1945         (*tested_tries)++;
1946         if (!time_before(jiffies, stopat) &&
1947             !shutdown_time_arrived() &&
1948             !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1949                 (*tested)++;
1950                 cver = READ_ONCE(rcu_torture_current_version) - cver;
1951                 gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1952                 WARN_ON(!cver && gps < 2);
1953                 pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1954         }
1955         if (selfpropcb) {
1956                 WRITE_ONCE(fcs.stop, 1);
1957                 cur_ops->sync(); /* Wait for running CB to complete. */
1958                 cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1959         }
1960
1961         if (selfpropcb) {
1962                 WARN_ON(READ_ONCE(fcs.stop) != 2);
1963                 destroy_rcu_head_on_stack(&fcs.rh);
1964         }
1965         schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
1966         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1967 }
1968
1969 /* Carry out call_rcu() forward-progress testing. */
1970 static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
1971 {
1972         unsigned long cver;
1973         unsigned long flags;
1974         unsigned long gps;
1975         int i;
1976         long n_launders;
1977         long n_launders_cb_snap;
1978         long n_launders_sa;
1979         long n_max_cbs;
1980         long n_max_gps;
1981         struct rcu_fwd_cb *rfcp;
1982         struct rcu_fwd_cb *rfcpn;
1983         unsigned long stopat;
1984         unsigned long stoppedat;
1985
1986         if (READ_ONCE(rcu_fwd_emergency_stop))
1987                 return; /* Get out of the way quickly, no GP wait! */
1988         if (!cur_ops->call)
1989                 return; /* Can't do call_rcu() fwd prog without ->call. */
1990
1991         /* Loop continuously posting RCU callbacks. */
1992         WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1993         cur_ops->sync(); /* Later readers see above write. */
1994         WRITE_ONCE(rfp->rcu_fwd_startat, jiffies);
1995         stopat = rfp->rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1996         n_launders = 0;
1997         rfp->n_launders_cb = 0; // Hoist initialization for multi-kthread
1998         n_launders_sa = 0;
1999         n_max_cbs = 0;
2000         n_max_gps = 0;
2001         for (i = 0; i < ARRAY_SIZE(rfp->n_launders_hist); i++)
2002                 rfp->n_launders_hist[i].n_launders = 0;
2003         cver = READ_ONCE(rcu_torture_current_version);
2004         gps = cur_ops->get_gp_seq();
2005         rfp->rcu_launder_gp_seq_start = gps;
2006         tick_dep_set_task(current, TICK_DEP_BIT_RCU);
2007         while (time_before(jiffies, stopat) &&
2008                !shutdown_time_arrived() &&
2009                !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
2010                 rfcp = READ_ONCE(rfp->rcu_fwd_cb_head);
2011                 rfcpn = NULL;
2012                 if (rfcp)
2013                         rfcpn = READ_ONCE(rfcp->rfc_next);
2014                 if (rfcpn) {
2015                         if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
2016                             ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
2017                                 break;
2018                         rfp->rcu_fwd_cb_head = rfcpn;
2019                         n_launders++;
2020                         n_launders_sa++;
2021                 } else {
2022                         rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
2023                         if (WARN_ON_ONCE(!rfcp)) {
2024                                 schedule_timeout_interruptible(1);
2025                                 continue;
2026                         }
2027                         n_max_cbs++;
2028                         n_launders_sa = 0;
2029                         rfcp->rfc_gps = 0;
2030                         rfcp->rfc_rfp = rfp;
2031                 }
2032                 cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
2033                 rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
2034                 if (tick_nohz_full_enabled()) {
2035                         local_irq_save(flags);
2036                         rcu_momentary_dyntick_idle();
2037                         local_irq_restore(flags);
2038                 }
2039         }
2040         stoppedat = jiffies;
2041         n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
2042         cver = READ_ONCE(rcu_torture_current_version) - cver;
2043         gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
2044         cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
2045         (void)rcu_torture_fwd_prog_cbfree(rfp);
2046
2047         if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
2048             !shutdown_time_arrived()) {
2049                 WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
2050                 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",
2051                          __func__,
2052                          stoppedat - rfp->rcu_fwd_startat, jiffies - stoppedat,
2053                          n_launders + n_max_cbs - n_launders_cb_snap,
2054                          n_launders, n_launders_sa,
2055                          n_max_gps, n_max_cbs, cver, gps);
2056                 rcu_torture_fwd_cb_hist(rfp);
2057         }
2058         schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
2059         tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
2060         WRITE_ONCE(rcu_fwd_cb_nodelay, false);
2061 }
2062
2063
2064 /*
2065  * OOM notifier, but this only prints diagnostic information for the
2066  * current forward-progress test.
2067  */
2068 static int rcutorture_oom_notify(struct notifier_block *self,
2069                                  unsigned long notused, void *nfreed)
2070 {
2071         struct rcu_fwd *rfp = rcu_fwds;
2072
2073         WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
2074              __func__);
2075         rcu_torture_fwd_cb_hist(rfp);
2076         rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rfp->rcu_fwd_startat)) / 2);
2077         WRITE_ONCE(rcu_fwd_emergency_stop, true);
2078         smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
2079         pr_info("%s: Freed %lu RCU callbacks.\n",
2080                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
2081         rcu_barrier();
2082         pr_info("%s: Freed %lu RCU callbacks.\n",
2083                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
2084         rcu_barrier();
2085         pr_info("%s: Freed %lu RCU callbacks.\n",
2086                 __func__, rcu_torture_fwd_prog_cbfree(rfp));
2087         smp_mb(); /* Frees before return to avoid redoing OOM. */
2088         (*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
2089         pr_info("%s returning after OOM processing.\n", __func__);
2090         return NOTIFY_OK;
2091 }
2092
2093 static struct notifier_block rcutorture_oom_nb = {
2094         .notifier_call = rcutorture_oom_notify
2095 };
2096
2097 /* Carry out grace-period forward-progress testing. */
2098 static int rcu_torture_fwd_prog(void *args)
2099 {
2100         struct rcu_fwd *rfp = args;
2101         int tested = 0;
2102         int tested_tries = 0;
2103
2104         VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
2105         rcu_bind_current_to_nocb();
2106         if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
2107                 set_user_nice(current, MAX_NICE);
2108         do {
2109                 schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
2110                 WRITE_ONCE(rcu_fwd_emergency_stop, false);
2111                 register_oom_notifier(&rcutorture_oom_nb);
2112                 if (!IS_ENABLED(CONFIG_TINY_RCU) ||
2113                     rcu_inkernel_boot_has_ended())
2114                         rcu_torture_fwd_prog_nr(rfp, &tested, &tested_tries);
2115                 if (rcu_inkernel_boot_has_ended())
2116                         rcu_torture_fwd_prog_cr(rfp);
2117                 unregister_oom_notifier(&rcutorture_oom_nb);
2118
2119                 /* Avoid slow periods, better to test when busy. */
2120                 stutter_wait("rcu_torture_fwd_prog");
2121         } while (!torture_must_stop());
2122         /* Short runs might not contain a valid forward-progress attempt. */
2123         WARN_ON(!tested && tested_tries >= 5);
2124         pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
2125         torture_kthread_stopping("rcu_torture_fwd_prog");
2126         return 0;
2127 }
2128
2129 /* If forward-progress checking is requested and feasible, spawn the thread. */
2130 static int __init rcu_torture_fwd_prog_init(void)
2131 {
2132         struct rcu_fwd *rfp;
2133
2134         if (!fwd_progress)
2135                 return 0; /* Not requested, so don't do it. */
2136         if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
2137             cur_ops == &rcu_busted_ops) {
2138                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
2139                 return 0;
2140         }
2141         if (stall_cpu > 0) {
2142                 VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
2143                 if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
2144                         return -EINVAL; /* In module, can fail back to user. */
2145                 WARN_ON(1); /* Make sure rcutorture notices conflict. */
2146                 return 0;
2147         }
2148         if (fwd_progress_holdoff <= 0)
2149                 fwd_progress_holdoff = 1;
2150         if (fwd_progress_div <= 0)
2151                 fwd_progress_div = 4;
2152         rfp = kzalloc(sizeof(*rfp), GFP_KERNEL);
2153         if (!rfp)
2154                 return -ENOMEM;
2155         spin_lock_init(&rfp->rcu_fwd_lock);
2156         rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;
2157         return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);
2158 }
2159
2160 /* Callback function for RCU barrier testing. */
2161 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
2162 {
2163         atomic_inc(&barrier_cbs_invoked);
2164 }
2165
2166 /* IPI handler to get callback posted on desired CPU, if online. */
2167 static void rcu_torture_barrier1cb(void *rcu_void)
2168 {
2169         struct rcu_head *rhp = rcu_void;
2170
2171         cur_ops->call(rhp, rcu_torture_barrier_cbf);
2172 }
2173
2174 /* kthread function to register callbacks used to test RCU barriers. */
2175 static int rcu_torture_barrier_cbs(void *arg)
2176 {
2177         long myid = (long)arg;
2178         bool lastphase = 0;
2179         bool newphase;
2180         struct rcu_head rcu;
2181
2182         init_rcu_head_on_stack(&rcu);
2183         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
2184         set_user_nice(current, MAX_NICE);
2185         do {
2186                 wait_event(barrier_cbs_wq[myid],
2187                            (newphase =
2188                             smp_load_acquire(&barrier_phase)) != lastphase ||
2189                            torture_must_stop());
2190                 lastphase = newphase;
2191                 if (torture_must_stop())
2192                         break;
2193                 /*
2194                  * The above smp_load_acquire() ensures barrier_phase load
2195                  * is ordered before the following ->call().
2196                  */
2197                 if (smp_call_function_single(myid, rcu_torture_barrier1cb,
2198                                              &rcu, 1)) {
2199                         // IPI failed, so use direct call from current CPU.
2200                         cur_ops->call(&rcu, rcu_torture_barrier_cbf);
2201                 }
2202                 if (atomic_dec_and_test(&barrier_cbs_count))
2203                         wake_up(&barrier_wq);
2204         } while (!torture_must_stop());
2205         if (cur_ops->cb_barrier != NULL)
2206                 cur_ops->cb_barrier();
2207         destroy_rcu_head_on_stack(&rcu);
2208         torture_kthread_stopping("rcu_torture_barrier_cbs");
2209         return 0;
2210 }
2211
2212 /* kthread function to drive and coordinate RCU barrier testing. */
2213 static int rcu_torture_barrier(void *arg)
2214 {
2215         int i;
2216
2217         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
2218         do {
2219                 atomic_set(&barrier_cbs_invoked, 0);
2220                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
2221                 /* Ensure barrier_phase ordered after prior assignments. */
2222                 smp_store_release(&barrier_phase, !barrier_phase);
2223                 for (i = 0; i < n_barrier_cbs; i++)
2224                         wake_up(&barrier_cbs_wq[i]);
2225                 wait_event(barrier_wq,
2226                            atomic_read(&barrier_cbs_count) == 0 ||
2227                            torture_must_stop());
2228                 if (torture_must_stop())
2229                         break;
2230                 n_barrier_attempts++;
2231                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
2232                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
2233                         n_rcu_torture_barrier_error++;
2234                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
2235                                atomic_read(&barrier_cbs_invoked),
2236                                n_barrier_cbs);
2237                         WARN_ON(1);
2238                         // Wait manually for the remaining callbacks
2239                         i = 0;
2240                         do {
2241                                 if (WARN_ON(i++ > HZ))
2242                                         i = INT_MIN;
2243                                 schedule_timeout_interruptible(1);
2244                                 cur_ops->cb_barrier();
2245                         } while (atomic_read(&barrier_cbs_invoked) !=
2246                                  n_barrier_cbs &&
2247                                  !torture_must_stop());
2248                         smp_mb(); // Can't trust ordering if broken.
2249                         if (!torture_must_stop())
2250                                 pr_err("Recovered: barrier_cbs_invoked = %d\n",
2251                                        atomic_read(&barrier_cbs_invoked));
2252                 } else {
2253                         n_barrier_successes++;
2254                 }
2255                 schedule_timeout_interruptible(HZ / 10);
2256         } while (!torture_must_stop());
2257         torture_kthread_stopping("rcu_torture_barrier");
2258         return 0;
2259 }
2260
2261 /* Initialize RCU barrier testing. */
2262 static int rcu_torture_barrier_init(void)
2263 {
2264         int i;
2265         int ret;
2266
2267         if (n_barrier_cbs <= 0)
2268                 return 0;
2269         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2270                 pr_alert("%s" TORTURE_FLAG
2271                          " Call or barrier ops missing for %s,\n",
2272                          torture_type, cur_ops->name);
2273                 pr_alert("%s" TORTURE_FLAG
2274                          " RCU barrier testing omitted from run.\n",
2275                          torture_type);
2276                 return 0;
2277         }
2278         atomic_set(&barrier_cbs_count, 0);
2279         atomic_set(&barrier_cbs_invoked, 0);
2280         barrier_cbs_tasks =
2281                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2282                         GFP_KERNEL);
2283         barrier_cbs_wq =
2284                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2285         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2286                 return -ENOMEM;
2287         for (i = 0; i < n_barrier_cbs; i++) {
2288                 init_waitqueue_head(&barrier_cbs_wq[i]);
2289                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
2290                                              (void *)(long)i,
2291                                              barrier_cbs_tasks[i]);
2292                 if (ret)
2293                         return ret;
2294         }
2295         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2296 }
2297
2298 /* Clean up after RCU barrier testing. */
2299 static void rcu_torture_barrier_cleanup(void)
2300 {
2301         int i;
2302
2303         torture_stop_kthread(rcu_torture_barrier, barrier_task);
2304         if (barrier_cbs_tasks != NULL) {
2305                 for (i = 0; i < n_barrier_cbs; i++)
2306                         torture_stop_kthread(rcu_torture_barrier_cbs,
2307                                              barrier_cbs_tasks[i]);
2308                 kfree(barrier_cbs_tasks);
2309                 barrier_cbs_tasks = NULL;
2310         }
2311         if (barrier_cbs_wq != NULL) {
2312                 kfree(barrier_cbs_wq);
2313                 barrier_cbs_wq = NULL;
2314         }
2315 }
2316
2317 static bool rcu_torture_can_boost(void)
2318 {
2319         static int boost_warn_once;
2320         int prio;
2321
2322         if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2323                 return false;
2324
2325         prio = rcu_get_gp_kthreads_prio();
2326         if (!prio)
2327                 return false;
2328
2329         if (prio < 2) {
2330                 if (boost_warn_once  == 1)
2331                         return false;
2332
2333                 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);
2334                 boost_warn_once = 1;
2335                 return false;
2336         }
2337
2338         return true;
2339 }
2340
2341 static enum cpuhp_state rcutor_hp;
2342
2343 static void
2344 rcu_torture_cleanup(void)
2345 {
2346         int firsttime;
2347         int flags = 0;
2348         unsigned long gp_seq = 0;
2349         int i;
2350
2351         if (torture_cleanup_begin()) {
2352                 if (cur_ops->cb_barrier != NULL)
2353                         cur_ops->cb_barrier();
2354                 return;
2355         }
2356         if (!cur_ops) {
2357                 torture_cleanup_end();
2358                 return;
2359         }
2360
2361         show_rcu_gp_kthreads();
2362         rcu_torture_barrier_cleanup();
2363         torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2364         torture_stop_kthread(rcu_torture_stall, stall_task);
2365         torture_stop_kthread(rcu_torture_writer, writer_task);
2366
2367         if (reader_tasks) {
2368                 for (i = 0; i < nrealreaders; i++)
2369                         torture_stop_kthread(rcu_torture_reader,
2370                                              reader_tasks[i]);
2371                 kfree(reader_tasks);
2372         }
2373         rcu_torture_current = NULL;
2374
2375         if (fakewriter_tasks) {
2376                 for (i = 0; i < nfakewriters; i++) {
2377                         torture_stop_kthread(rcu_torture_fakewriter,
2378                                              fakewriter_tasks[i]);
2379                 }
2380                 kfree(fakewriter_tasks);
2381                 fakewriter_tasks = NULL;
2382         }
2383
2384         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2385         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2386         pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2387                  cur_ops->name, gp_seq, flags);
2388         torture_stop_kthread(rcu_torture_stats, stats_task);
2389         torture_stop_kthread(rcu_torture_fqs, fqs_task);
2390         if (rcu_torture_can_boost())
2391                 cpuhp_remove_state(rcutor_hp);
2392
2393         /*
2394          * Wait for all RCU callbacks to fire, then do torture-type-specific
2395          * cleanup operations.
2396          */
2397         if (cur_ops->cb_barrier != NULL)
2398                 cur_ops->cb_barrier();
2399         if (cur_ops->cleanup != NULL)
2400                 cur_ops->cleanup();
2401
2402         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2403
2404         if (err_segs_recorded) {
2405                 pr_alert("Failure/close-call rcutorture reader segments:\n");
2406                 if (rt_read_nsegs == 0)
2407                         pr_alert("\t: No segments recorded!!!\n");
2408                 firsttime = 1;
2409                 for (i = 0; i < rt_read_nsegs; i++) {
2410                         pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2411                         if (err_segs[i].rt_delay_jiffies != 0) {
2412                                 pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2413                                         err_segs[i].rt_delay_jiffies);
2414                                 firsttime = 0;
2415                         }
2416                         if (err_segs[i].rt_delay_ms != 0) {
2417                                 pr_cont("%s%ldms", firsttime ? "" : "+",
2418                                         err_segs[i].rt_delay_ms);
2419                                 firsttime = 0;
2420                         }
2421                         if (err_segs[i].rt_delay_us != 0) {
2422                                 pr_cont("%s%ldus", firsttime ? "" : "+",
2423                                         err_segs[i].rt_delay_us);
2424                                 firsttime = 0;
2425                         }
2426                         pr_cont("%s\n",
2427                                 err_segs[i].rt_preempted ? "preempted" : "");
2428
2429                 }
2430         }
2431         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2432                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2433         else if (torture_onoff_failures())
2434                 rcu_torture_print_module_parms(cur_ops,
2435                                                "End of test: RCU_HOTPLUG");
2436         else
2437                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2438         torture_cleanup_end();
2439 }
2440
2441 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2442 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2443 {
2444 }
2445
2446 static void rcu_torture_err_cb(struct rcu_head *rhp)
2447 {
2448         /*
2449          * This -might- happen due to race conditions, but is unlikely.
2450          * The scenario that leads to this happening is that the
2451          * first of the pair of duplicate callbacks is queued,
2452          * someone else starts a grace period that includes that
2453          * callback, then the second of the pair must wait for the
2454          * next grace period.  Unlikely, but can happen.  If it
2455          * does happen, the debug-objects subsystem won't have splatted.
2456          */
2457         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2458 }
2459 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2460
2461 /*
2462  * Verify that double-free causes debug-objects to complain, but only
2463  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2464  * cannot be carried out.
2465  */
2466 static void rcu_test_debug_objects(void)
2467 {
2468 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2469         struct rcu_head rh1;
2470         struct rcu_head rh2;
2471
2472         init_rcu_head_on_stack(&rh1);
2473         init_rcu_head_on_stack(&rh2);
2474         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2475
2476         /* Try to queue the rh2 pair of callbacks for the same grace period. */
2477         preempt_disable(); /* Prevent preemption from interrupting test. */
2478         rcu_read_lock(); /* Make it impossible to finish a grace period. */
2479         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2480         local_irq_disable(); /* Make it harder to start a new grace period. */
2481         call_rcu(&rh2, rcu_torture_leak_cb);
2482         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2483         local_irq_enable();
2484         rcu_read_unlock();
2485         preempt_enable();
2486
2487         /* Wait for them all to get done so we can safely return. */
2488         rcu_barrier();
2489         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2490         destroy_rcu_head_on_stack(&rh1);
2491         destroy_rcu_head_on_stack(&rh2);
2492 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2493         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2494 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2495 }
2496
2497 static void rcutorture_sync(void)
2498 {
2499         static unsigned long n;
2500
2501         if (cur_ops->sync && !(++n & 0xfff))
2502                 cur_ops->sync();
2503 }
2504
2505 static int __init
2506 rcu_torture_init(void)
2507 {
2508         long i;
2509         int cpu;
2510         int firsterr = 0;
2511         static struct rcu_torture_ops *torture_ops[] = {
2512                 &rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2513                 &busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
2514                 &tasks_tracing_ops, &trivial_ops,
2515         };
2516
2517         if (!torture_init_begin(torture_type, verbose))
2518                 return -EBUSY;
2519
2520         /* Process args and tell the world that the torturer is on the job. */
2521         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2522                 cur_ops = torture_ops[i];
2523                 if (strcmp(torture_type, cur_ops->name) == 0)
2524                         break;
2525         }
2526         if (i == ARRAY_SIZE(torture_ops)) {
2527                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2528                          torture_type);
2529                 pr_alert("rcu-torture types:");
2530                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2531                         pr_cont(" %s", torture_ops[i]->name);
2532                 pr_cont("\n");
2533                 WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2534                 firsterr = -EINVAL;
2535                 cur_ops = NULL;
2536                 goto unwind;
2537         }
2538         if (cur_ops->fqs == NULL && fqs_duration != 0) {
2539                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2540                 fqs_duration = 0;
2541         }
2542         if (cur_ops->init)
2543                 cur_ops->init();
2544
2545         if (nreaders >= 0) {
2546                 nrealreaders = nreaders;
2547         } else {
2548                 nrealreaders = num_online_cpus() - 2 - nreaders;
2549                 if (nrealreaders <= 0)
2550                         nrealreaders = 1;
2551         }
2552         rcu_torture_print_module_parms(cur_ops, "Start of test");
2553
2554         /* Set up the freelist. */
2555
2556         INIT_LIST_HEAD(&rcu_torture_freelist);
2557         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2558                 rcu_tortures[i].rtort_mbtest = 0;
2559                 list_add_tail(&rcu_tortures[i].rtort_free,
2560                               &rcu_torture_freelist);
2561         }
2562
2563         /* Initialize the statistics so that each run gets its own numbers. */
2564
2565         rcu_torture_current = NULL;
2566         rcu_torture_current_version = 0;
2567         atomic_set(&n_rcu_torture_alloc, 0);
2568         atomic_set(&n_rcu_torture_alloc_fail, 0);
2569         atomic_set(&n_rcu_torture_free, 0);
2570         atomic_set(&n_rcu_torture_mberror, 0);
2571         atomic_set(&n_rcu_torture_error, 0);
2572         n_rcu_torture_barrier_error = 0;
2573         n_rcu_torture_boost_ktrerror = 0;
2574         n_rcu_torture_boost_rterror = 0;
2575         n_rcu_torture_boost_failure = 0;
2576         n_rcu_torture_boosts = 0;
2577         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2578                 atomic_set(&rcu_torture_wcount[i], 0);
2579         for_each_possible_cpu(cpu) {
2580                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2581                         per_cpu(rcu_torture_count, cpu)[i] = 0;
2582                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
2583                 }
2584         }
2585         err_segs_recorded = 0;
2586         rt_read_nsegs = 0;
2587
2588         /* Start up the kthreads. */
2589
2590         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2591                                           writer_task);
2592         if (firsterr)
2593                 goto unwind;
2594         if (nfakewriters > 0) {
2595                 fakewriter_tasks = kcalloc(nfakewriters,
2596                                            sizeof(fakewriter_tasks[0]),
2597                                            GFP_KERNEL);
2598                 if (fakewriter_tasks == NULL) {
2599                         VERBOSE_TOROUT_ERRSTRING("out of memory");
2600                         firsterr = -ENOMEM;
2601                         goto unwind;
2602                 }
2603         }
2604         for (i = 0; i < nfakewriters; i++) {
2605                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
2606                                                   NULL, fakewriter_tasks[i]);
2607                 if (firsterr)
2608                         goto unwind;
2609         }
2610         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2611                                GFP_KERNEL);
2612         if (reader_tasks == NULL) {
2613                 VERBOSE_TOROUT_ERRSTRING("out of memory");
2614                 firsterr = -ENOMEM;
2615                 goto unwind;
2616         }
2617         for (i = 0; i < nrealreaders; i++) {
2618                 firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2619                                                   reader_tasks[i]);
2620                 if (firsterr)
2621                         goto unwind;
2622         }
2623         if (stat_interval > 0) {
2624                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2625                                                   stats_task);
2626                 if (firsterr)
2627                         goto unwind;
2628         }
2629         if (test_no_idle_hz && shuffle_interval > 0) {
2630                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
2631                 if (firsterr)
2632                         goto unwind;
2633         }
2634         if (stutter < 0)
2635                 stutter = 0;
2636         if (stutter) {
2637                 int t;
2638
2639                 t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
2640                 firsterr = torture_stutter_init(stutter * HZ, t);
2641                 if (firsterr)
2642                         goto unwind;
2643         }
2644         if (fqs_duration < 0)
2645                 fqs_duration = 0;
2646         if (fqs_duration) {
2647                 /* Create the fqs thread */
2648                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2649                                                   fqs_task);
2650                 if (firsterr)
2651                         goto unwind;
2652         }
2653         if (test_boost_interval < 1)
2654                 test_boost_interval = 1;
2655         if (test_boost_duration < 2)
2656                 test_boost_duration = 2;
2657         if (rcu_torture_can_boost()) {
2658
2659                 boost_starttime = jiffies + test_boost_interval * HZ;
2660
2661                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2662                                              rcutorture_booster_init,
2663                                              rcutorture_booster_cleanup);
2664                 if (firsterr < 0)
2665                         goto unwind;
2666                 rcutor_hp = firsterr;
2667         }
2668         shutdown_jiffies = jiffies + shutdown_secs * HZ;
2669         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2670         if (firsterr)
2671                 goto unwind;
2672         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2673                                       rcutorture_sync);
2674         if (firsterr)
2675                 goto unwind;
2676         firsterr = rcu_torture_stall_init();
2677         if (firsterr)
2678                 goto unwind;
2679         firsterr = rcu_torture_fwd_prog_init();
2680         if (firsterr)
2681                 goto unwind;
2682         firsterr = rcu_torture_barrier_init();
2683         if (firsterr)
2684                 goto unwind;
2685         if (object_debug)
2686                 rcu_test_debug_objects();
2687         torture_init_end();
2688         return 0;
2689
2690 unwind:
2691         torture_init_end();
2692         rcu_torture_cleanup();
2693         return firsterr;
2694 }
2695
2696 module_init(rcu_torture_init);
2697 module_exit(rcu_torture_cleanup);