1 /* 2 * Read-Copy Update module-based torture test facility 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, you can access it online at 16 * http://www.gnu.org/licenses/gpl-2.0.html. 17 * 18 * Copyright (C) IBM Corporation, 2005, 2006 19 * 20 * Authors: Paul E. McKenney <paulmck@us.ibm.com> 21 * Josh Triplett <josh@joshtriplett.org> 22 * 23 * See also: Documentation/RCU/torture.txt 24 */ 25 #include <linux/types.h> 26 #include <linux/kernel.h> 27 #include <linux/init.h> 28 #include <linux/module.h> 29 #include <linux/kthread.h> 30 #include <linux/err.h> 31 #include <linux/spinlock.h> 32 #include <linux/smp.h> 33 #include <linux/rcupdate.h> 34 #include <linux/interrupt.h> 35 #include <linux/sched.h> 36 #include <linux/atomic.h> 37 #include <linux/bitops.h> 38 #include <linux/completion.h> 39 #include <linux/moduleparam.h> 40 #include <linux/percpu.h> 41 #include <linux/notifier.h> 42 #include <linux/reboot.h> 43 #include <linux/freezer.h> 44 #include <linux/cpu.h> 45 #include <linux/delay.h> 46 #include <linux/stat.h> 47 #include <linux/srcu.h> 48 #include <linux/slab.h> 49 #include <linux/trace_clock.h> 50 #include <asm/byteorder.h> 51 #include <linux/torture.h> 52 #include <linux/vmalloc.h> 53 54 MODULE_LICENSE("GPL"); 55 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>"); 56 57 58 torture_param(int, cbflood_inter_holdoff, HZ, 59 "Holdoff between floods (jiffies)"); 60 torture_param(int, cbflood_intra_holdoff, 1, 61 "Holdoff between bursts (jiffies)"); 62 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable"); 63 torture_param(int, cbflood_n_per_burst, 20000, 64 "# callbacks per burst in flood"); 65 torture_param(int, fqs_duration, 0, 66 "Duration of fqs bursts (us), 0 to disable"); 67 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)"); 68 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)"); 69 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives"); 70 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives"); 71 torture_param(bool, gp_normal, false, 72 "Use normal (non-expedited) GP wait primitives"); 73 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives"); 74 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers"); 75 torture_param(int, n_barrier_cbs, 0, 76 "# of callbacks/kthreads for barrier testing"); 77 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads"); 78 torture_param(int, nreaders, -1, "Number of RCU reader threads"); 79 torture_param(int, object_debug, 0, 80 "Enable debug-object double call_rcu() testing"); 81 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)"); 82 torture_param(int, onoff_interval, 0, 83 "Time between CPU hotplugs (s), 0=disable"); 84 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles"); 85 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable."); 86 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable."); 87 torture_param(int, stall_cpu_holdoff, 10, 88 "Time to wait before starting stall (s)."); 89 torture_param(int, stat_interval, 60, 90 "Number of seconds between stats printk()s"); 91 torture_param(int, stutter, 5, "Number of seconds to run/halt test"); 92 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes."); 93 torture_param(int, test_boost_duration, 4, 94 "Duration of each boost test, seconds."); 95 torture_param(int, test_boost_interval, 7, 96 "Interval between boost tests, seconds."); 97 torture_param(bool, test_no_idle_hz, true, 98 "Test support for tickless idle CPUs"); 99 torture_param(bool, verbose, true, 100 "Enable verbose debugging printk()s"); 101 102 static char *torture_type = "rcu"; 103 module_param(torture_type, charp, 0444); 104 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)"); 105 106 static int nrealreaders; 107 static int ncbflooders; 108 static struct task_struct *writer_task; 109 static struct task_struct **fakewriter_tasks; 110 static struct task_struct **reader_tasks; 111 static struct task_struct *stats_task; 112 static struct task_struct **cbflood_task; 113 static struct task_struct *fqs_task; 114 static struct task_struct *boost_tasks[NR_CPUS]; 115 static struct task_struct *stall_task; 116 static struct task_struct **barrier_cbs_tasks; 117 static struct task_struct *barrier_task; 118 119 #define RCU_TORTURE_PIPE_LEN 10 120 121 struct rcu_torture { 122 struct rcu_head rtort_rcu; 123 int rtort_pipe_count; 124 struct list_head rtort_free; 125 int rtort_mbtest; 126 }; 127 128 static LIST_HEAD(rcu_torture_freelist); 129 static struct rcu_torture __rcu *rcu_torture_current; 130 static unsigned long rcu_torture_current_version; 131 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN]; 132 static DEFINE_SPINLOCK(rcu_torture_lock); 133 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], 134 rcu_torture_count) = { 0 }; 135 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], 136 rcu_torture_batch) = { 0 }; 137 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1]; 138 static atomic_t n_rcu_torture_alloc; 139 static atomic_t n_rcu_torture_alloc_fail; 140 static atomic_t n_rcu_torture_free; 141 static atomic_t n_rcu_torture_mberror; 142 static atomic_t n_rcu_torture_error; 143 static long n_rcu_torture_barrier_error; 144 static long n_rcu_torture_boost_ktrerror; 145 static long n_rcu_torture_boost_rterror; 146 static long n_rcu_torture_boost_failure; 147 static long n_rcu_torture_boosts; 148 static long n_rcu_torture_timers; 149 static long n_barrier_attempts; 150 static long n_barrier_successes; 151 static atomic_long_t n_cbfloods; 152 static struct list_head rcu_torture_removed; 153 154 static int rcu_torture_writer_state; 155 #define RTWS_FIXED_DELAY 0 156 #define RTWS_DELAY 1 157 #define RTWS_REPLACE 2 158 #define RTWS_DEF_FREE 3 159 #define RTWS_EXP_SYNC 4 160 #define RTWS_COND_GET 5 161 #define RTWS_COND_SYNC 6 162 #define RTWS_SYNC 7 163 #define RTWS_STUTTER 8 164 #define RTWS_STOPPING 9 165 166 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE) 167 #define RCUTORTURE_RUNNABLE_INIT 1 168 #else 169 #define RCUTORTURE_RUNNABLE_INIT 0 170 #endif 171 static int torture_runnable = RCUTORTURE_RUNNABLE_INIT; 172 module_param(torture_runnable, int, 0444); 173 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot"); 174 175 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) 176 #define rcu_can_boost() 1 177 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ 178 #define rcu_can_boost() 0 179 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ 180 181 #ifdef CONFIG_RCU_TRACE 182 static u64 notrace rcu_trace_clock_local(void) 183 { 184 u64 ts = trace_clock_local(); 185 unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC); 186 return ts; 187 } 188 #else /* #ifdef CONFIG_RCU_TRACE */ 189 static u64 notrace rcu_trace_clock_local(void) 190 { 191 return 0ULL; 192 } 193 #endif /* #else #ifdef CONFIG_RCU_TRACE */ 194 195 static unsigned long boost_starttime; /* jiffies of next boost test start. */ 196 static DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */ 197 /* and boost task create/destroy. */ 198 static atomic_t barrier_cbs_count; /* Barrier callbacks registered. */ 199 static bool barrier_phase; /* Test phase. */ 200 static atomic_t barrier_cbs_invoked; /* Barrier callbacks invoked. */ 201 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */ 202 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq); 203 204 /* 205 * Allocate an element from the rcu_tortures pool. 206 */ 207 static struct rcu_torture * 208 rcu_torture_alloc(void) 209 { 210 struct list_head *p; 211 212 spin_lock_bh(&rcu_torture_lock); 213 if (list_empty(&rcu_torture_freelist)) { 214 atomic_inc(&n_rcu_torture_alloc_fail); 215 spin_unlock_bh(&rcu_torture_lock); 216 return NULL; 217 } 218 atomic_inc(&n_rcu_torture_alloc); 219 p = rcu_torture_freelist.next; 220 list_del_init(p); 221 spin_unlock_bh(&rcu_torture_lock); 222 return container_of(p, struct rcu_torture, rtort_free); 223 } 224 225 /* 226 * Free an element to the rcu_tortures pool. 227 */ 228 static void 229 rcu_torture_free(struct rcu_torture *p) 230 { 231 atomic_inc(&n_rcu_torture_free); 232 spin_lock_bh(&rcu_torture_lock); 233 list_add_tail(&p->rtort_free, &rcu_torture_freelist); 234 spin_unlock_bh(&rcu_torture_lock); 235 } 236 237 /* 238 * Operations vector for selecting different types of tests. 239 */ 240 241 struct rcu_torture_ops { 242 int ttype; 243 void (*init)(void); 244 int (*readlock)(void); 245 void (*read_delay)(struct torture_random_state *rrsp); 246 void (*readunlock)(int idx); 247 int (*completed)(void); 248 void (*deferred_free)(struct rcu_torture *p); 249 void (*sync)(void); 250 void (*exp_sync)(void); 251 unsigned long (*get_state)(void); 252 void (*cond_sync)(unsigned long oldstate); 253 void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 254 void (*cb_barrier)(void); 255 void (*fqs)(void); 256 void (*stats)(void); 257 int irq_capable; 258 int can_boost; 259 const char *name; 260 }; 261 262 static struct rcu_torture_ops *cur_ops; 263 264 /* 265 * Definitions for rcu torture testing. 266 */ 267 268 static int rcu_torture_read_lock(void) __acquires(RCU) 269 { 270 rcu_read_lock(); 271 return 0; 272 } 273 274 static void rcu_read_delay(struct torture_random_state *rrsp) 275 { 276 const unsigned long shortdelay_us = 200; 277 const unsigned long longdelay_ms = 50; 278 279 /* We want a short delay sometimes to make a reader delay the grace 280 * period, and we want a long delay occasionally to trigger 281 * force_quiescent_state. */ 282 283 if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) 284 mdelay(longdelay_ms); 285 if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) 286 udelay(shortdelay_us); 287 #ifdef CONFIG_PREEMPT 288 if (!preempt_count() && 289 !(torture_random(rrsp) % (nrealreaders * 20000))) 290 preempt_schedule(); /* No QS if preempt_disable() in effect */ 291 #endif 292 } 293 294 static void rcu_torture_read_unlock(int idx) __releases(RCU) 295 { 296 rcu_read_unlock(); 297 } 298 299 static int rcu_torture_completed(void) 300 { 301 return rcu_batches_completed(); 302 } 303 304 /* 305 * Update callback in the pipe. This should be invoked after a grace period. 306 */ 307 static bool 308 rcu_torture_pipe_update_one(struct rcu_torture *rp) 309 { 310 int i; 311 312 i = rp->rtort_pipe_count; 313 if (i > RCU_TORTURE_PIPE_LEN) 314 i = RCU_TORTURE_PIPE_LEN; 315 atomic_inc(&rcu_torture_wcount[i]); 316 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) { 317 rp->rtort_mbtest = 0; 318 return true; 319 } 320 return false; 321 } 322 323 /* 324 * Update all callbacks in the pipe. Suitable for synchronous grace-period 325 * primitives. 326 */ 327 static void 328 rcu_torture_pipe_update(struct rcu_torture *old_rp) 329 { 330 struct rcu_torture *rp; 331 struct rcu_torture *rp1; 332 333 if (old_rp) 334 list_add(&old_rp->rtort_free, &rcu_torture_removed); 335 list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) { 336 if (rcu_torture_pipe_update_one(rp)) { 337 list_del(&rp->rtort_free); 338 rcu_torture_free(rp); 339 } 340 } 341 } 342 343 static void 344 rcu_torture_cb(struct rcu_head *p) 345 { 346 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu); 347 348 if (torture_must_stop_irq()) { 349 /* Test is ending, just drop callbacks on the floor. */ 350 /* The next initialization will pick up the pieces. */ 351 return; 352 } 353 if (rcu_torture_pipe_update_one(rp)) 354 rcu_torture_free(rp); 355 else 356 cur_ops->deferred_free(rp); 357 } 358 359 static int rcu_no_completed(void) 360 { 361 return 0; 362 } 363 364 static void rcu_torture_deferred_free(struct rcu_torture *p) 365 { 366 call_rcu(&p->rtort_rcu, rcu_torture_cb); 367 } 368 369 static void rcu_sync_torture_init(void) 370 { 371 INIT_LIST_HEAD(&rcu_torture_removed); 372 } 373 374 static struct rcu_torture_ops rcu_ops = { 375 .ttype = RCU_FLAVOR, 376 .init = rcu_sync_torture_init, 377 .readlock = rcu_torture_read_lock, 378 .read_delay = rcu_read_delay, 379 .readunlock = rcu_torture_read_unlock, 380 .completed = rcu_torture_completed, 381 .deferred_free = rcu_torture_deferred_free, 382 .sync = synchronize_rcu, 383 .exp_sync = synchronize_rcu_expedited, 384 .get_state = get_state_synchronize_rcu, 385 .cond_sync = cond_synchronize_rcu, 386 .call = call_rcu, 387 .cb_barrier = rcu_barrier, 388 .fqs = rcu_force_quiescent_state, 389 .stats = NULL, 390 .irq_capable = 1, 391 .can_boost = rcu_can_boost(), 392 .name = "rcu" 393 }; 394 395 /* 396 * Definitions for rcu_bh torture testing. 397 */ 398 399 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH) 400 { 401 rcu_read_lock_bh(); 402 return 0; 403 } 404 405 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH) 406 { 407 rcu_read_unlock_bh(); 408 } 409 410 static int rcu_bh_torture_completed(void) 411 { 412 return rcu_batches_completed_bh(); 413 } 414 415 static void rcu_bh_torture_deferred_free(struct rcu_torture *p) 416 { 417 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb); 418 } 419 420 static struct rcu_torture_ops rcu_bh_ops = { 421 .ttype = RCU_BH_FLAVOR, 422 .init = rcu_sync_torture_init, 423 .readlock = rcu_bh_torture_read_lock, 424 .read_delay = rcu_read_delay, /* just reuse rcu's version. */ 425 .readunlock = rcu_bh_torture_read_unlock, 426 .completed = rcu_bh_torture_completed, 427 .deferred_free = rcu_bh_torture_deferred_free, 428 .sync = synchronize_rcu_bh, 429 .exp_sync = synchronize_rcu_bh_expedited, 430 .call = call_rcu_bh, 431 .cb_barrier = rcu_barrier_bh, 432 .fqs = rcu_bh_force_quiescent_state, 433 .stats = NULL, 434 .irq_capable = 1, 435 .name = "rcu_bh" 436 }; 437 438 /* 439 * Don't even think about trying any of these in real life!!! 440 * The names includes "busted", and they really means it! 441 * The only purpose of these functions is to provide a buggy RCU 442 * implementation to make sure that rcutorture correctly emits 443 * buggy-RCU error messages. 444 */ 445 static void rcu_busted_torture_deferred_free(struct rcu_torture *p) 446 { 447 /* This is a deliberate bug for testing purposes only! */ 448 rcu_torture_cb(&p->rtort_rcu); 449 } 450 451 static void synchronize_rcu_busted(void) 452 { 453 /* This is a deliberate bug for testing purposes only! */ 454 } 455 456 static void 457 call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) 458 { 459 /* This is a deliberate bug for testing purposes only! */ 460 func(head); 461 } 462 463 static struct rcu_torture_ops rcu_busted_ops = { 464 .ttype = INVALID_RCU_FLAVOR, 465 .init = rcu_sync_torture_init, 466 .readlock = rcu_torture_read_lock, 467 .read_delay = rcu_read_delay, /* just reuse rcu's version. */ 468 .readunlock = rcu_torture_read_unlock, 469 .completed = rcu_no_completed, 470 .deferred_free = rcu_busted_torture_deferred_free, 471 .sync = synchronize_rcu_busted, 472 .exp_sync = synchronize_rcu_busted, 473 .call = call_rcu_busted, 474 .cb_barrier = NULL, 475 .fqs = NULL, 476 .stats = NULL, 477 .irq_capable = 1, 478 .name = "rcu_busted" 479 }; 480 481 /* 482 * Definitions for srcu torture testing. 483 */ 484 485 DEFINE_STATIC_SRCU(srcu_ctl); 486 487 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl) 488 { 489 return srcu_read_lock(&srcu_ctl); 490 } 491 492 static void srcu_read_delay(struct torture_random_state *rrsp) 493 { 494 long delay; 495 const long uspertick = 1000000 / HZ; 496 const long longdelay = 10; 497 498 /* We want there to be long-running readers, but not all the time. */ 499 500 delay = torture_random(rrsp) % 501 (nrealreaders * 2 * longdelay * uspertick); 502 if (!delay) 503 schedule_timeout_interruptible(longdelay); 504 else 505 rcu_read_delay(rrsp); 506 } 507 508 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl) 509 { 510 srcu_read_unlock(&srcu_ctl, idx); 511 } 512 513 static int srcu_torture_completed(void) 514 { 515 return srcu_batches_completed(&srcu_ctl); 516 } 517 518 static void srcu_torture_deferred_free(struct rcu_torture *rp) 519 { 520 call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb); 521 } 522 523 static void srcu_torture_synchronize(void) 524 { 525 synchronize_srcu(&srcu_ctl); 526 } 527 528 static void srcu_torture_call(struct rcu_head *head, 529 void (*func)(struct rcu_head *head)) 530 { 531 call_srcu(&srcu_ctl, head, func); 532 } 533 534 static void srcu_torture_barrier(void) 535 { 536 srcu_barrier(&srcu_ctl); 537 } 538 539 static void srcu_torture_stats(void) 540 { 541 int cpu; 542 int idx = srcu_ctl.completed & 0x1; 543 544 pr_alert("%s%s per-CPU(idx=%d):", 545 torture_type, TORTURE_FLAG, idx); 546 for_each_possible_cpu(cpu) { 547 long c0, c1; 548 549 c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx]; 550 c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]; 551 pr_cont(" %d(%ld,%ld)", cpu, c0, c1); 552 } 553 pr_cont("\n"); 554 } 555 556 static void srcu_torture_synchronize_expedited(void) 557 { 558 synchronize_srcu_expedited(&srcu_ctl); 559 } 560 561 static struct rcu_torture_ops srcu_ops = { 562 .ttype = SRCU_FLAVOR, 563 .init = rcu_sync_torture_init, 564 .readlock = srcu_torture_read_lock, 565 .read_delay = srcu_read_delay, 566 .readunlock = srcu_torture_read_unlock, 567 .completed = srcu_torture_completed, 568 .deferred_free = srcu_torture_deferred_free, 569 .sync = srcu_torture_synchronize, 570 .exp_sync = srcu_torture_synchronize_expedited, 571 .call = srcu_torture_call, 572 .cb_barrier = srcu_torture_barrier, 573 .stats = srcu_torture_stats, 574 .name = "srcu" 575 }; 576 577 /* 578 * Definitions for sched torture testing. 579 */ 580 581 static int sched_torture_read_lock(void) 582 { 583 preempt_disable(); 584 return 0; 585 } 586 587 static void sched_torture_read_unlock(int idx) 588 { 589 preempt_enable(); 590 } 591 592 static void rcu_sched_torture_deferred_free(struct rcu_torture *p) 593 { 594 call_rcu_sched(&p->rtort_rcu, rcu_torture_cb); 595 } 596 597 static struct rcu_torture_ops sched_ops = { 598 .ttype = RCU_SCHED_FLAVOR, 599 .init = rcu_sync_torture_init, 600 .readlock = sched_torture_read_lock, 601 .read_delay = rcu_read_delay, /* just reuse rcu's version. */ 602 .readunlock = sched_torture_read_unlock, 603 .completed = rcu_no_completed, 604 .deferred_free = rcu_sched_torture_deferred_free, 605 .sync = synchronize_sched, 606 .exp_sync = synchronize_sched_expedited, 607 .call = call_rcu_sched, 608 .cb_barrier = rcu_barrier_sched, 609 .fqs = rcu_sched_force_quiescent_state, 610 .stats = NULL, 611 .irq_capable = 1, 612 .name = "sched" 613 }; 614 615 #ifdef CONFIG_TASKS_RCU 616 617 /* 618 * Definitions for RCU-tasks torture testing. 619 */ 620 621 static int tasks_torture_read_lock(void) 622 { 623 return 0; 624 } 625 626 static void tasks_torture_read_unlock(int idx) 627 { 628 } 629 630 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p) 631 { 632 call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb); 633 } 634 635 static struct rcu_torture_ops tasks_ops = { 636 .ttype = RCU_TASKS_FLAVOR, 637 .init = rcu_sync_torture_init, 638 .readlock = tasks_torture_read_lock, 639 .read_delay = rcu_read_delay, /* just reuse rcu's version. */ 640 .readunlock = tasks_torture_read_unlock, 641 .completed = rcu_no_completed, 642 .deferred_free = rcu_tasks_torture_deferred_free, 643 .sync = synchronize_rcu_tasks, 644 .exp_sync = synchronize_rcu_tasks, 645 .call = call_rcu_tasks, 646 .cb_barrier = rcu_barrier_tasks, 647 .fqs = NULL, 648 .stats = NULL, 649 .irq_capable = 1, 650 .name = "tasks" 651 }; 652 653 #define RCUTORTURE_TASKS_OPS &tasks_ops, 654 655 #else /* #ifdef CONFIG_TASKS_RCU */ 656 657 #define RCUTORTURE_TASKS_OPS 658 659 #endif /* #else #ifdef CONFIG_TASKS_RCU */ 660 661 /* 662 * RCU torture priority-boost testing. Runs one real-time thread per 663 * CPU for moderate bursts, repeatedly registering RCU callbacks and 664 * spinning waiting for them to be invoked. If a given callback takes 665 * too long to be invoked, we assume that priority inversion has occurred. 666 */ 667 668 struct rcu_boost_inflight { 669 struct rcu_head rcu; 670 int inflight; 671 }; 672 673 static void rcu_torture_boost_cb(struct rcu_head *head) 674 { 675 struct rcu_boost_inflight *rbip = 676 container_of(head, struct rcu_boost_inflight, rcu); 677 678 smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */ 679 rbip->inflight = 0; 680 } 681 682 static int rcu_torture_boost(void *arg) 683 { 684 unsigned long call_rcu_time; 685 unsigned long endtime; 686 unsigned long oldstarttime; 687 struct rcu_boost_inflight rbi = { .inflight = 0 }; 688 struct sched_param sp; 689 690 VERBOSE_TOROUT_STRING("rcu_torture_boost started"); 691 692 /* Set real-time priority. */ 693 sp.sched_priority = 1; 694 if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) { 695 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!"); 696 n_rcu_torture_boost_rterror++; 697 } 698 699 init_rcu_head_on_stack(&rbi.rcu); 700 /* Each pass through the following loop does one boost-test cycle. */ 701 do { 702 /* Wait for the next test interval. */ 703 oldstarttime = boost_starttime; 704 while (ULONG_CMP_LT(jiffies, oldstarttime)) { 705 schedule_timeout_interruptible(oldstarttime - jiffies); 706 stutter_wait("rcu_torture_boost"); 707 if (torture_must_stop()) 708 goto checkwait; 709 } 710 711 /* Do one boost-test interval. */ 712 endtime = oldstarttime + test_boost_duration * HZ; 713 call_rcu_time = jiffies; 714 while (ULONG_CMP_LT(jiffies, endtime)) { 715 /* If we don't have a callback in flight, post one. */ 716 if (!rbi.inflight) { 717 smp_mb(); /* RCU core before ->inflight = 1. */ 718 rbi.inflight = 1; 719 call_rcu(&rbi.rcu, rcu_torture_boost_cb); 720 if (jiffies - call_rcu_time > 721 test_boost_duration * HZ - HZ / 2) { 722 VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed"); 723 n_rcu_torture_boost_failure++; 724 } 725 call_rcu_time = jiffies; 726 } 727 cond_resched_rcu_qs(); 728 stutter_wait("rcu_torture_boost"); 729 if (torture_must_stop()) 730 goto checkwait; 731 } 732 733 /* 734 * Set the start time of the next test interval. 735 * Yes, this is vulnerable to long delays, but such 736 * delays simply cause a false negative for the next 737 * interval. Besides, we are running at RT priority, 738 * so delays should be relatively rare. 739 */ 740 while (oldstarttime == boost_starttime && 741 !kthread_should_stop()) { 742 if (mutex_trylock(&boost_mutex)) { 743 boost_starttime = jiffies + 744 test_boost_interval * HZ; 745 n_rcu_torture_boosts++; 746 mutex_unlock(&boost_mutex); 747 break; 748 } 749 schedule_timeout_uninterruptible(1); 750 } 751 752 /* Go do the stutter. */ 753 checkwait: stutter_wait("rcu_torture_boost"); 754 } while (!torture_must_stop()); 755 756 /* Clean up and exit. */ 757 while (!kthread_should_stop() || rbi.inflight) { 758 torture_shutdown_absorb("rcu_torture_boost"); 759 schedule_timeout_uninterruptible(1); 760 } 761 smp_mb(); /* order accesses to ->inflight before stack-frame death. */ 762 destroy_rcu_head_on_stack(&rbi.rcu); 763 torture_kthread_stopping("rcu_torture_boost"); 764 return 0; 765 } 766 767 static void rcu_torture_cbflood_cb(struct rcu_head *rhp) 768 { 769 } 770 771 /* 772 * RCU torture callback-flood kthread. Repeatedly induces bursts of calls 773 * to call_rcu() or analogous, increasing the probability of occurrence 774 * of callback-overflow corner cases. 775 */ 776 static int 777 rcu_torture_cbflood(void *arg) 778 { 779 int err = 1; 780 int i; 781 int j; 782 struct rcu_head *rhp; 783 784 if (cbflood_n_per_burst > 0 && 785 cbflood_inter_holdoff > 0 && 786 cbflood_intra_holdoff > 0 && 787 cur_ops->call && 788 cur_ops->cb_barrier) { 789 rhp = vmalloc(sizeof(*rhp) * 790 cbflood_n_burst * cbflood_n_per_burst); 791 err = !rhp; 792 } 793 if (err) { 794 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM"); 795 while (!torture_must_stop()) 796 schedule_timeout_interruptible(HZ); 797 return 0; 798 } 799 VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started"); 800 do { 801 schedule_timeout_interruptible(cbflood_inter_holdoff); 802 atomic_long_inc(&n_cbfloods); 803 WARN_ON(signal_pending(current)); 804 for (i = 0; i < cbflood_n_burst; i++) { 805 for (j = 0; j < cbflood_n_per_burst; j++) { 806 cur_ops->call(&rhp[i * cbflood_n_per_burst + j], 807 rcu_torture_cbflood_cb); 808 } 809 schedule_timeout_interruptible(cbflood_intra_holdoff); 810 WARN_ON(signal_pending(current)); 811 } 812 cur_ops->cb_barrier(); 813 stutter_wait("rcu_torture_cbflood"); 814 } while (!torture_must_stop()); 815 torture_kthread_stopping("rcu_torture_cbflood"); 816 return 0; 817 } 818 819 /* 820 * RCU torture force-quiescent-state kthread. Repeatedly induces 821 * bursts of calls to force_quiescent_state(), increasing the probability 822 * of occurrence of some important types of race conditions. 823 */ 824 static int 825 rcu_torture_fqs(void *arg) 826 { 827 unsigned long fqs_resume_time; 828 int fqs_burst_remaining; 829 830 VERBOSE_TOROUT_STRING("rcu_torture_fqs task started"); 831 do { 832 fqs_resume_time = jiffies + fqs_stutter * HZ; 833 while (ULONG_CMP_LT(jiffies, fqs_resume_time) && 834 !kthread_should_stop()) { 835 schedule_timeout_interruptible(1); 836 } 837 fqs_burst_remaining = fqs_duration; 838 while (fqs_burst_remaining > 0 && 839 !kthread_should_stop()) { 840 cur_ops->fqs(); 841 udelay(fqs_holdoff); 842 fqs_burst_remaining -= fqs_holdoff; 843 } 844 stutter_wait("rcu_torture_fqs"); 845 } while (!torture_must_stop()); 846 torture_kthread_stopping("rcu_torture_fqs"); 847 return 0; 848 } 849 850 /* 851 * RCU torture writer kthread. Repeatedly substitutes a new structure 852 * for that pointed to by rcu_torture_current, freeing the old structure 853 * after a series of grace periods (the "pipeline"). 854 */ 855 static int 856 rcu_torture_writer(void *arg) 857 { 858 unsigned long gp_snap; 859 bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal; 860 bool gp_sync1 = gp_sync; 861 int i; 862 struct rcu_torture *rp; 863 struct rcu_torture *old_rp; 864 static DEFINE_TORTURE_RANDOM(rand); 865 int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC, 866 RTWS_COND_GET, RTWS_SYNC }; 867 int nsynctypes = 0; 868 869 VERBOSE_TOROUT_STRING("rcu_torture_writer task started"); 870 871 /* Initialize synctype[] array. If none set, take default. */ 872 if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync) 873 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true; 874 if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) 875 synctype[nsynctypes++] = RTWS_COND_GET; 876 else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) 877 pr_alert("rcu_torture_writer: gp_cond without primitives.\n"); 878 if (gp_exp1 && cur_ops->exp_sync) 879 synctype[nsynctypes++] = RTWS_EXP_SYNC; 880 else if (gp_exp && !cur_ops->exp_sync) 881 pr_alert("rcu_torture_writer: gp_exp without primitives.\n"); 882 if (gp_normal1 && cur_ops->deferred_free) 883 synctype[nsynctypes++] = RTWS_DEF_FREE; 884 else if (gp_normal && !cur_ops->deferred_free) 885 pr_alert("rcu_torture_writer: gp_normal without primitives.\n"); 886 if (gp_sync1 && cur_ops->sync) 887 synctype[nsynctypes++] = RTWS_SYNC; 888 else if (gp_sync && !cur_ops->sync) 889 pr_alert("rcu_torture_writer: gp_sync without primitives.\n"); 890 if (WARN_ONCE(nsynctypes == 0, 891 "rcu_torture_writer: No update-side primitives.\n")) { 892 /* 893 * No updates primitives, so don't try updating. 894 * The resulting test won't be testing much, hence the 895 * above WARN_ONCE(). 896 */ 897 rcu_torture_writer_state = RTWS_STOPPING; 898 torture_kthread_stopping("rcu_torture_writer"); 899 } 900 901 do { 902 rcu_torture_writer_state = RTWS_FIXED_DELAY; 903 schedule_timeout_uninterruptible(1); 904 rp = rcu_torture_alloc(); 905 if (rp == NULL) 906 continue; 907 rp->rtort_pipe_count = 0; 908 rcu_torture_writer_state = RTWS_DELAY; 909 udelay(torture_random(&rand) & 0x3ff); 910 rcu_torture_writer_state = RTWS_REPLACE; 911 old_rp = rcu_dereference_check(rcu_torture_current, 912 current == writer_task); 913 rp->rtort_mbtest = 1; 914 rcu_assign_pointer(rcu_torture_current, rp); 915 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */ 916 if (old_rp) { 917 i = old_rp->rtort_pipe_count; 918 if (i > RCU_TORTURE_PIPE_LEN) 919 i = RCU_TORTURE_PIPE_LEN; 920 atomic_inc(&rcu_torture_wcount[i]); 921 old_rp->rtort_pipe_count++; 922 switch (synctype[torture_random(&rand) % nsynctypes]) { 923 case RTWS_DEF_FREE: 924 rcu_torture_writer_state = RTWS_DEF_FREE; 925 cur_ops->deferred_free(old_rp); 926 break; 927 case RTWS_EXP_SYNC: 928 rcu_torture_writer_state = RTWS_EXP_SYNC; 929 cur_ops->exp_sync(); 930 rcu_torture_pipe_update(old_rp); 931 break; 932 case RTWS_COND_GET: 933 rcu_torture_writer_state = RTWS_COND_GET; 934 gp_snap = cur_ops->get_state(); 935 i = torture_random(&rand) % 16; 936 if (i != 0) 937 schedule_timeout_interruptible(i); 938 udelay(torture_random(&rand) % 1000); 939 rcu_torture_writer_state = RTWS_COND_SYNC; 940 cur_ops->cond_sync(gp_snap); 941 rcu_torture_pipe_update(old_rp); 942 break; 943 case RTWS_SYNC: 944 rcu_torture_writer_state = RTWS_SYNC; 945 cur_ops->sync(); 946 rcu_torture_pipe_update(old_rp); 947 break; 948 default: 949 WARN_ON_ONCE(1); 950 break; 951 } 952 } 953 rcutorture_record_progress(++rcu_torture_current_version); 954 rcu_torture_writer_state = RTWS_STUTTER; 955 stutter_wait("rcu_torture_writer"); 956 } while (!torture_must_stop()); 957 rcu_torture_writer_state = RTWS_STOPPING; 958 torture_kthread_stopping("rcu_torture_writer"); 959 return 0; 960 } 961 962 /* 963 * RCU torture fake writer kthread. Repeatedly calls sync, with a random 964 * delay between calls. 965 */ 966 static int 967 rcu_torture_fakewriter(void *arg) 968 { 969 DEFINE_TORTURE_RANDOM(rand); 970 971 VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started"); 972 set_user_nice(current, MAX_NICE); 973 974 do { 975 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10); 976 udelay(torture_random(&rand) & 0x3ff); 977 if (cur_ops->cb_barrier != NULL && 978 torture_random(&rand) % (nfakewriters * 8) == 0) { 979 cur_ops->cb_barrier(); 980 } else if (gp_normal == gp_exp) { 981 if (torture_random(&rand) & 0x80) 982 cur_ops->sync(); 983 else 984 cur_ops->exp_sync(); 985 } else if (gp_normal) { 986 cur_ops->sync(); 987 } else { 988 cur_ops->exp_sync(); 989 } 990 stutter_wait("rcu_torture_fakewriter"); 991 } while (!torture_must_stop()); 992 993 torture_kthread_stopping("rcu_torture_fakewriter"); 994 return 0; 995 } 996 997 static void rcutorture_trace_dump(void) 998 { 999 static atomic_t beenhere = ATOMIC_INIT(0); 1000 1001 if (atomic_read(&beenhere)) 1002 return; 1003 if (atomic_xchg(&beenhere, 1) != 0) 1004 return; 1005 ftrace_dump(DUMP_ALL); 1006 } 1007 1008 /* 1009 * RCU torture reader from timer handler. Dereferences rcu_torture_current, 1010 * incrementing the corresponding element of the pipeline array. The 1011 * counter in the element should never be greater than 1, otherwise, the 1012 * RCU implementation is broken. 1013 */ 1014 static void rcu_torture_timer(unsigned long unused) 1015 { 1016 int idx; 1017 int completed; 1018 int completed_end; 1019 static DEFINE_TORTURE_RANDOM(rand); 1020 static DEFINE_SPINLOCK(rand_lock); 1021 struct rcu_torture *p; 1022 int pipe_count; 1023 unsigned long long ts; 1024 1025 idx = cur_ops->readlock(); 1026 completed = cur_ops->completed(); 1027 ts = rcu_trace_clock_local(); 1028 p = rcu_dereference_check(rcu_torture_current, 1029 rcu_read_lock_bh_held() || 1030 rcu_read_lock_sched_held() || 1031 srcu_read_lock_held(&srcu_ctl)); 1032 if (p == NULL) { 1033 /* Leave because rcu_torture_writer is not yet underway */ 1034 cur_ops->readunlock(idx); 1035 return; 1036 } 1037 if (p->rtort_mbtest == 0) 1038 atomic_inc(&n_rcu_torture_mberror); 1039 spin_lock(&rand_lock); 1040 cur_ops->read_delay(&rand); 1041 n_rcu_torture_timers++; 1042 spin_unlock(&rand_lock); 1043 preempt_disable(); 1044 pipe_count = p->rtort_pipe_count; 1045 if (pipe_count > RCU_TORTURE_PIPE_LEN) { 1046 /* Should not happen, but... */ 1047 pipe_count = RCU_TORTURE_PIPE_LEN; 1048 } 1049 completed_end = cur_ops->completed(); 1050 if (pipe_count > 1) { 1051 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts, 1052 completed, completed_end); 1053 rcutorture_trace_dump(); 1054 } 1055 __this_cpu_inc(rcu_torture_count[pipe_count]); 1056 completed = completed_end - completed; 1057 if (completed > RCU_TORTURE_PIPE_LEN) { 1058 /* Should not happen, but... */ 1059 completed = RCU_TORTURE_PIPE_LEN; 1060 } 1061 __this_cpu_inc(rcu_torture_batch[completed]); 1062 preempt_enable(); 1063 cur_ops->readunlock(idx); 1064 } 1065 1066 /* 1067 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current, 1068 * incrementing the corresponding element of the pipeline array. The 1069 * counter in the element should never be greater than 1, otherwise, the 1070 * RCU implementation is broken. 1071 */ 1072 static int 1073 rcu_torture_reader(void *arg) 1074 { 1075 int completed; 1076 int completed_end; 1077 int idx; 1078 DEFINE_TORTURE_RANDOM(rand); 1079 struct rcu_torture *p; 1080 int pipe_count; 1081 struct timer_list t; 1082 unsigned long long ts; 1083 1084 VERBOSE_TOROUT_STRING("rcu_torture_reader task started"); 1085 set_user_nice(current, MAX_NICE); 1086 if (irqreader && cur_ops->irq_capable) 1087 setup_timer_on_stack(&t, rcu_torture_timer, 0); 1088 1089 do { 1090 if (irqreader && cur_ops->irq_capable) { 1091 if (!timer_pending(&t)) 1092 mod_timer(&t, jiffies + 1); 1093 } 1094 idx = cur_ops->readlock(); 1095 completed = cur_ops->completed(); 1096 ts = rcu_trace_clock_local(); 1097 p = rcu_dereference_check(rcu_torture_current, 1098 rcu_read_lock_bh_held() || 1099 rcu_read_lock_sched_held() || 1100 srcu_read_lock_held(&srcu_ctl)); 1101 if (p == NULL) { 1102 /* Wait for rcu_torture_writer to get underway */ 1103 cur_ops->readunlock(idx); 1104 schedule_timeout_interruptible(HZ); 1105 continue; 1106 } 1107 if (p->rtort_mbtest == 0) 1108 atomic_inc(&n_rcu_torture_mberror); 1109 cur_ops->read_delay(&rand); 1110 preempt_disable(); 1111 pipe_count = p->rtort_pipe_count; 1112 if (pipe_count > RCU_TORTURE_PIPE_LEN) { 1113 /* Should not happen, but... */ 1114 pipe_count = RCU_TORTURE_PIPE_LEN; 1115 } 1116 completed_end = cur_ops->completed(); 1117 if (pipe_count > 1) { 1118 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, 1119 ts, completed, completed_end); 1120 rcutorture_trace_dump(); 1121 } 1122 __this_cpu_inc(rcu_torture_count[pipe_count]); 1123 completed = completed_end - completed; 1124 if (completed > RCU_TORTURE_PIPE_LEN) { 1125 /* Should not happen, but... */ 1126 completed = RCU_TORTURE_PIPE_LEN; 1127 } 1128 __this_cpu_inc(rcu_torture_batch[completed]); 1129 preempt_enable(); 1130 cur_ops->readunlock(idx); 1131 cond_resched_rcu_qs(); 1132 stutter_wait("rcu_torture_reader"); 1133 } while (!torture_must_stop()); 1134 if (irqreader && cur_ops->irq_capable) { 1135 del_timer_sync(&t); 1136 destroy_timer_on_stack(&t); 1137 } 1138 torture_kthread_stopping("rcu_torture_reader"); 1139 return 0; 1140 } 1141 1142 /* 1143 * Print torture statistics. Caller must ensure that there is only 1144 * one call to this function at a given time!!! This is normally 1145 * accomplished by relying on the module system to only have one copy 1146 * of the module loaded, and then by giving the rcu_torture_stats 1147 * kthread full control (or the init/cleanup functions when rcu_torture_stats 1148 * thread is not running). 1149 */ 1150 static void 1151 rcu_torture_stats_print(void) 1152 { 1153 int cpu; 1154 int i; 1155 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; 1156 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 }; 1157 static unsigned long rtcv_snap = ULONG_MAX; 1158 1159 for_each_possible_cpu(cpu) { 1160 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { 1161 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i]; 1162 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i]; 1163 } 1164 } 1165 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) { 1166 if (pipesummary[i] != 0) 1167 break; 1168 } 1169 1170 pr_alert("%s%s ", torture_type, TORTURE_FLAG); 1171 pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ", 1172 rcu_torture_current, 1173 rcu_torture_current_version, 1174 list_empty(&rcu_torture_freelist), 1175 atomic_read(&n_rcu_torture_alloc), 1176 atomic_read(&n_rcu_torture_alloc_fail), 1177 atomic_read(&n_rcu_torture_free)); 1178 pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ", 1179 atomic_read(&n_rcu_torture_mberror), 1180 n_rcu_torture_boost_ktrerror, 1181 n_rcu_torture_boost_rterror); 1182 pr_cont("rtbf: %ld rtb: %ld nt: %ld ", 1183 n_rcu_torture_boost_failure, 1184 n_rcu_torture_boosts, 1185 n_rcu_torture_timers); 1186 torture_onoff_stats(); 1187 pr_cont("barrier: %ld/%ld:%ld ", 1188 n_barrier_successes, 1189 n_barrier_attempts, 1190 n_rcu_torture_barrier_error); 1191 pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods)); 1192 1193 pr_alert("%s%s ", torture_type, TORTURE_FLAG); 1194 if (atomic_read(&n_rcu_torture_mberror) != 0 || 1195 n_rcu_torture_barrier_error != 0 || 1196 n_rcu_torture_boost_ktrerror != 0 || 1197 n_rcu_torture_boost_rterror != 0 || 1198 n_rcu_torture_boost_failure != 0 || 1199 i > 1) { 1200 pr_cont("%s", "!!! "); 1201 atomic_inc(&n_rcu_torture_error); 1202 WARN_ON_ONCE(1); 1203 } 1204 pr_cont("Reader Pipe: "); 1205 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) 1206 pr_cont(" %ld", pipesummary[i]); 1207 pr_cont("\n"); 1208 1209 pr_alert("%s%s ", torture_type, TORTURE_FLAG); 1210 pr_cont("Reader Batch: "); 1211 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) 1212 pr_cont(" %ld", batchsummary[i]); 1213 pr_cont("\n"); 1214 1215 pr_alert("%s%s ", torture_type, TORTURE_FLAG); 1216 pr_cont("Free-Block Circulation: "); 1217 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { 1218 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i])); 1219 } 1220 pr_cont("\n"); 1221 1222 if (cur_ops->stats) 1223 cur_ops->stats(); 1224 if (rtcv_snap == rcu_torture_current_version && 1225 rcu_torture_current != NULL) { 1226 int __maybe_unused flags; 1227 unsigned long __maybe_unused gpnum; 1228 unsigned long __maybe_unused completed; 1229 1230 rcutorture_get_gp_data(cur_ops->ttype, 1231 &flags, &gpnum, &completed); 1232 pr_alert("??? Writer stall state %d g%lu c%lu f%#x\n", 1233 rcu_torture_writer_state, 1234 gpnum, completed, flags); 1235 show_rcu_gp_kthreads(); 1236 rcutorture_trace_dump(); 1237 } 1238 rtcv_snap = rcu_torture_current_version; 1239 } 1240 1241 /* 1242 * Periodically prints torture statistics, if periodic statistics printing 1243 * was specified via the stat_interval module parameter. 1244 */ 1245 static int 1246 rcu_torture_stats(void *arg) 1247 { 1248 VERBOSE_TOROUT_STRING("rcu_torture_stats task started"); 1249 do { 1250 schedule_timeout_interruptible(stat_interval * HZ); 1251 rcu_torture_stats_print(); 1252 torture_shutdown_absorb("rcu_torture_stats"); 1253 } while (!torture_must_stop()); 1254 torture_kthread_stopping("rcu_torture_stats"); 1255 return 0; 1256 } 1257 1258 static inline void 1259 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) 1260 { 1261 pr_alert("%s" TORTURE_FLAG 1262 "--- %s: nreaders=%d nfakewriters=%d " 1263 "stat_interval=%d verbose=%d test_no_idle_hz=%d " 1264 "shuffle_interval=%d stutter=%d irqreader=%d " 1265 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d " 1266 "test_boost=%d/%d test_boost_interval=%d " 1267 "test_boost_duration=%d shutdown_secs=%d " 1268 "stall_cpu=%d stall_cpu_holdoff=%d " 1269 "n_barrier_cbs=%d " 1270 "onoff_interval=%d onoff_holdoff=%d\n", 1271 torture_type, tag, nrealreaders, nfakewriters, 1272 stat_interval, verbose, test_no_idle_hz, shuffle_interval, 1273 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter, 1274 test_boost, cur_ops->can_boost, 1275 test_boost_interval, test_boost_duration, shutdown_secs, 1276 stall_cpu, stall_cpu_holdoff, 1277 n_barrier_cbs, 1278 onoff_interval, onoff_holdoff); 1279 } 1280 1281 static void rcutorture_booster_cleanup(int cpu) 1282 { 1283 struct task_struct *t; 1284 1285 if (boost_tasks[cpu] == NULL) 1286 return; 1287 mutex_lock(&boost_mutex); 1288 t = boost_tasks[cpu]; 1289 boost_tasks[cpu] = NULL; 1290 mutex_unlock(&boost_mutex); 1291 1292 /* This must be outside of the mutex, otherwise deadlock! */ 1293 torture_stop_kthread(rcu_torture_boost, t); 1294 } 1295 1296 static int rcutorture_booster_init(int cpu) 1297 { 1298 int retval; 1299 1300 if (boost_tasks[cpu] != NULL) 1301 return 0; /* Already created, nothing more to do. */ 1302 1303 /* Don't allow time recalculation while creating a new task. */ 1304 mutex_lock(&boost_mutex); 1305 VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task"); 1306 boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL, 1307 cpu_to_node(cpu), 1308 "rcu_torture_boost"); 1309 if (IS_ERR(boost_tasks[cpu])) { 1310 retval = PTR_ERR(boost_tasks[cpu]); 1311 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed"); 1312 n_rcu_torture_boost_ktrerror++; 1313 boost_tasks[cpu] = NULL; 1314 mutex_unlock(&boost_mutex); 1315 return retval; 1316 } 1317 kthread_bind(boost_tasks[cpu], cpu); 1318 wake_up_process(boost_tasks[cpu]); 1319 mutex_unlock(&boost_mutex); 1320 return 0; 1321 } 1322 1323 /* 1324 * CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then 1325 * induces a CPU stall for the time specified by stall_cpu. 1326 */ 1327 static int rcu_torture_stall(void *args) 1328 { 1329 unsigned long stop_at; 1330 1331 VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); 1332 if (stall_cpu_holdoff > 0) { 1333 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff"); 1334 schedule_timeout_interruptible(stall_cpu_holdoff * HZ); 1335 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff"); 1336 } 1337 if (!kthread_should_stop()) { 1338 stop_at = get_seconds() + stall_cpu; 1339 /* RCU CPU stall is expected behavior in following code. */ 1340 pr_alert("rcu_torture_stall start.\n"); 1341 rcu_read_lock(); 1342 preempt_disable(); 1343 while (ULONG_CMP_LT(get_seconds(), stop_at)) 1344 continue; /* Induce RCU CPU stall warning. */ 1345 preempt_enable(); 1346 rcu_read_unlock(); 1347 pr_alert("rcu_torture_stall end.\n"); 1348 } 1349 torture_shutdown_absorb("rcu_torture_stall"); 1350 while (!kthread_should_stop()) 1351 schedule_timeout_interruptible(10 * HZ); 1352 return 0; 1353 } 1354 1355 /* Spawn CPU-stall kthread, if stall_cpu specified. */ 1356 static int __init rcu_torture_stall_init(void) 1357 { 1358 if (stall_cpu <= 0) 1359 return 0; 1360 return torture_create_kthread(rcu_torture_stall, NULL, stall_task); 1361 } 1362 1363 /* Callback function for RCU barrier testing. */ 1364 static void rcu_torture_barrier_cbf(struct rcu_head *rcu) 1365 { 1366 atomic_inc(&barrier_cbs_invoked); 1367 } 1368 1369 /* kthread function to register callbacks used to test RCU barriers. */ 1370 static int rcu_torture_barrier_cbs(void *arg) 1371 { 1372 long myid = (long)arg; 1373 bool lastphase = 0; 1374 bool newphase; 1375 struct rcu_head rcu; 1376 1377 init_rcu_head_on_stack(&rcu); 1378 VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started"); 1379 set_user_nice(current, MAX_NICE); 1380 do { 1381 wait_event(barrier_cbs_wq[myid], 1382 (newphase = 1383 ACCESS_ONCE(barrier_phase)) != lastphase || 1384 torture_must_stop()); 1385 lastphase = newphase; 1386 smp_mb(); /* ensure barrier_phase load before ->call(). */ 1387 if (torture_must_stop()) 1388 break; 1389 cur_ops->call(&rcu, rcu_torture_barrier_cbf); 1390 if (atomic_dec_and_test(&barrier_cbs_count)) 1391 wake_up(&barrier_wq); 1392 } while (!torture_must_stop()); 1393 if (cur_ops->cb_barrier != NULL) 1394 cur_ops->cb_barrier(); 1395 destroy_rcu_head_on_stack(&rcu); 1396 torture_kthread_stopping("rcu_torture_barrier_cbs"); 1397 return 0; 1398 } 1399 1400 /* kthread function to drive and coordinate RCU barrier testing. */ 1401 static int rcu_torture_barrier(void *arg) 1402 { 1403 int i; 1404 1405 VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting"); 1406 do { 1407 atomic_set(&barrier_cbs_invoked, 0); 1408 atomic_set(&barrier_cbs_count, n_barrier_cbs); 1409 smp_mb(); /* Ensure barrier_phase after prior assignments. */ 1410 barrier_phase = !barrier_phase; 1411 for (i = 0; i < n_barrier_cbs; i++) 1412 wake_up(&barrier_cbs_wq[i]); 1413 wait_event(barrier_wq, 1414 atomic_read(&barrier_cbs_count) == 0 || 1415 torture_must_stop()); 1416 if (torture_must_stop()) 1417 break; 1418 n_barrier_attempts++; 1419 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */ 1420 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) { 1421 n_rcu_torture_barrier_error++; 1422 WARN_ON_ONCE(1); 1423 } 1424 n_barrier_successes++; 1425 schedule_timeout_interruptible(HZ / 10); 1426 } while (!torture_must_stop()); 1427 torture_kthread_stopping("rcu_torture_barrier"); 1428 return 0; 1429 } 1430 1431 /* Initialize RCU barrier testing. */ 1432 static int rcu_torture_barrier_init(void) 1433 { 1434 int i; 1435 int ret; 1436 1437 if (n_barrier_cbs == 0) 1438 return 0; 1439 if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) { 1440 pr_alert("%s" TORTURE_FLAG 1441 " Call or barrier ops missing for %s,\n", 1442 torture_type, cur_ops->name); 1443 pr_alert("%s" TORTURE_FLAG 1444 " RCU barrier testing omitted from run.\n", 1445 torture_type); 1446 return 0; 1447 } 1448 atomic_set(&barrier_cbs_count, 0); 1449 atomic_set(&barrier_cbs_invoked, 0); 1450 barrier_cbs_tasks = 1451 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]), 1452 GFP_KERNEL); 1453 barrier_cbs_wq = 1454 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]), 1455 GFP_KERNEL); 1456 if (barrier_cbs_tasks == NULL || !barrier_cbs_wq) 1457 return -ENOMEM; 1458 for (i = 0; i < n_barrier_cbs; i++) { 1459 init_waitqueue_head(&barrier_cbs_wq[i]); 1460 ret = torture_create_kthread(rcu_torture_barrier_cbs, 1461 (void *)(long)i, 1462 barrier_cbs_tasks[i]); 1463 if (ret) 1464 return ret; 1465 } 1466 return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task); 1467 } 1468 1469 /* Clean up after RCU barrier testing. */ 1470 static void rcu_torture_barrier_cleanup(void) 1471 { 1472 int i; 1473 1474 torture_stop_kthread(rcu_torture_barrier, barrier_task); 1475 if (barrier_cbs_tasks != NULL) { 1476 for (i = 0; i < n_barrier_cbs; i++) 1477 torture_stop_kthread(rcu_torture_barrier_cbs, 1478 barrier_cbs_tasks[i]); 1479 kfree(barrier_cbs_tasks); 1480 barrier_cbs_tasks = NULL; 1481 } 1482 if (barrier_cbs_wq != NULL) { 1483 kfree(barrier_cbs_wq); 1484 barrier_cbs_wq = NULL; 1485 } 1486 } 1487 1488 static int rcutorture_cpu_notify(struct notifier_block *self, 1489 unsigned long action, void *hcpu) 1490 { 1491 long cpu = (long)hcpu; 1492 1493 switch (action) { 1494 case CPU_ONLINE: 1495 case CPU_DOWN_FAILED: 1496 (void)rcutorture_booster_init(cpu); 1497 break; 1498 case CPU_DOWN_PREPARE: 1499 rcutorture_booster_cleanup(cpu); 1500 break; 1501 default: 1502 break; 1503 } 1504 return NOTIFY_OK; 1505 } 1506 1507 static struct notifier_block rcutorture_cpu_nb = { 1508 .notifier_call = rcutorture_cpu_notify, 1509 }; 1510 1511 static void 1512 rcu_torture_cleanup(void) 1513 { 1514 int i; 1515 1516 rcutorture_record_test_transition(); 1517 if (torture_cleanup_begin()) { 1518 if (cur_ops->cb_barrier != NULL) 1519 cur_ops->cb_barrier(); 1520 return; 1521 } 1522 1523 rcu_torture_barrier_cleanup(); 1524 torture_stop_kthread(rcu_torture_stall, stall_task); 1525 torture_stop_kthread(rcu_torture_writer, writer_task); 1526 1527 if (reader_tasks) { 1528 for (i = 0; i < nrealreaders; i++) 1529 torture_stop_kthread(rcu_torture_reader, 1530 reader_tasks[i]); 1531 kfree(reader_tasks); 1532 } 1533 rcu_torture_current = NULL; 1534 1535 if (fakewriter_tasks) { 1536 for (i = 0; i < nfakewriters; i++) { 1537 torture_stop_kthread(rcu_torture_fakewriter, 1538 fakewriter_tasks[i]); 1539 } 1540 kfree(fakewriter_tasks); 1541 fakewriter_tasks = NULL; 1542 } 1543 1544 torture_stop_kthread(rcu_torture_stats, stats_task); 1545 torture_stop_kthread(rcu_torture_fqs, fqs_task); 1546 for (i = 0; i < ncbflooders; i++) 1547 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]); 1548 if ((test_boost == 1 && cur_ops->can_boost) || 1549 test_boost == 2) { 1550 unregister_cpu_notifier(&rcutorture_cpu_nb); 1551 for_each_possible_cpu(i) 1552 rcutorture_booster_cleanup(i); 1553 } 1554 1555 /* Wait for all RCU callbacks to fire. */ 1556 1557 if (cur_ops->cb_barrier != NULL) 1558 cur_ops->cb_barrier(); 1559 1560 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */ 1561 1562 if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error) 1563 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE"); 1564 else if (torture_onoff_failures()) 1565 rcu_torture_print_module_parms(cur_ops, 1566 "End of test: RCU_HOTPLUG"); 1567 else 1568 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS"); 1569 torture_cleanup_end(); 1570 } 1571 1572 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 1573 static void rcu_torture_leak_cb(struct rcu_head *rhp) 1574 { 1575 } 1576 1577 static void rcu_torture_err_cb(struct rcu_head *rhp) 1578 { 1579 /* 1580 * This -might- happen due to race conditions, but is unlikely. 1581 * The scenario that leads to this happening is that the 1582 * first of the pair of duplicate callbacks is queued, 1583 * someone else starts a grace period that includes that 1584 * callback, then the second of the pair must wait for the 1585 * next grace period. Unlikely, but can happen. If it 1586 * does happen, the debug-objects subsystem won't have splatted. 1587 */ 1588 pr_alert("rcutorture: duplicated callback was invoked.\n"); 1589 } 1590 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 1591 1592 /* 1593 * Verify that double-free causes debug-objects to complain, but only 1594 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y. Otherwise, say that the test 1595 * cannot be carried out. 1596 */ 1597 static void rcu_test_debug_objects(void) 1598 { 1599 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 1600 struct rcu_head rh1; 1601 struct rcu_head rh2; 1602 1603 init_rcu_head_on_stack(&rh1); 1604 init_rcu_head_on_stack(&rh2); 1605 pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n"); 1606 1607 /* Try to queue the rh2 pair of callbacks for the same grace period. */ 1608 preempt_disable(); /* Prevent preemption from interrupting test. */ 1609 rcu_read_lock(); /* Make it impossible to finish a grace period. */ 1610 call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */ 1611 local_irq_disable(); /* Make it harder to start a new grace period. */ 1612 call_rcu(&rh2, rcu_torture_leak_cb); 1613 call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */ 1614 local_irq_enable(); 1615 rcu_read_unlock(); 1616 preempt_enable(); 1617 1618 /* Wait for them all to get done so we can safely return. */ 1619 rcu_barrier(); 1620 pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n"); 1621 destroy_rcu_head_on_stack(&rh1); 1622 destroy_rcu_head_on_stack(&rh2); 1623 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 1624 pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n"); 1625 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 1626 } 1627 1628 static int __init 1629 rcu_torture_init(void) 1630 { 1631 int i; 1632 int cpu; 1633 int firsterr = 0; 1634 static struct rcu_torture_ops *torture_ops[] = { 1635 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops, 1636 RCUTORTURE_TASKS_OPS 1637 }; 1638 1639 if (!torture_init_begin(torture_type, verbose, &torture_runnable)) 1640 return -EBUSY; 1641 1642 /* Process args and tell the world that the torturer is on the job. */ 1643 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) { 1644 cur_ops = torture_ops[i]; 1645 if (strcmp(torture_type, cur_ops->name) == 0) 1646 break; 1647 } 1648 if (i == ARRAY_SIZE(torture_ops)) { 1649 pr_alert("rcu-torture: invalid torture type: \"%s\"\n", 1650 torture_type); 1651 pr_alert("rcu-torture types:"); 1652 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) 1653 pr_alert(" %s", torture_ops[i]->name); 1654 pr_alert("\n"); 1655 torture_init_end(); 1656 return -EINVAL; 1657 } 1658 if (cur_ops->fqs == NULL && fqs_duration != 0) { 1659 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n"); 1660 fqs_duration = 0; 1661 } 1662 if (cur_ops->init) 1663 cur_ops->init(); /* no "goto unwind" prior to this point!!! */ 1664 1665 if (nreaders >= 0) { 1666 nrealreaders = nreaders; 1667 } else { 1668 nrealreaders = num_online_cpus() - 1; 1669 if (nrealreaders <= 0) 1670 nrealreaders = 1; 1671 } 1672 rcu_torture_print_module_parms(cur_ops, "Start of test"); 1673 1674 /* Set up the freelist. */ 1675 1676 INIT_LIST_HEAD(&rcu_torture_freelist); 1677 for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) { 1678 rcu_tortures[i].rtort_mbtest = 0; 1679 list_add_tail(&rcu_tortures[i].rtort_free, 1680 &rcu_torture_freelist); 1681 } 1682 1683 /* Initialize the statistics so that each run gets its own numbers. */ 1684 1685 rcu_torture_current = NULL; 1686 rcu_torture_current_version = 0; 1687 atomic_set(&n_rcu_torture_alloc, 0); 1688 atomic_set(&n_rcu_torture_alloc_fail, 0); 1689 atomic_set(&n_rcu_torture_free, 0); 1690 atomic_set(&n_rcu_torture_mberror, 0); 1691 atomic_set(&n_rcu_torture_error, 0); 1692 n_rcu_torture_barrier_error = 0; 1693 n_rcu_torture_boost_ktrerror = 0; 1694 n_rcu_torture_boost_rterror = 0; 1695 n_rcu_torture_boost_failure = 0; 1696 n_rcu_torture_boosts = 0; 1697 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) 1698 atomic_set(&rcu_torture_wcount[i], 0); 1699 for_each_possible_cpu(cpu) { 1700 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) { 1701 per_cpu(rcu_torture_count, cpu)[i] = 0; 1702 per_cpu(rcu_torture_batch, cpu)[i] = 0; 1703 } 1704 } 1705 1706 /* Start up the kthreads. */ 1707 1708 firsterr = torture_create_kthread(rcu_torture_writer, NULL, 1709 writer_task); 1710 if (firsterr) 1711 goto unwind; 1712 fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]), 1713 GFP_KERNEL); 1714 if (fakewriter_tasks == NULL) { 1715 VERBOSE_TOROUT_ERRSTRING("out of memory"); 1716 firsterr = -ENOMEM; 1717 goto unwind; 1718 } 1719 for (i = 0; i < nfakewriters; i++) { 1720 firsterr = torture_create_kthread(rcu_torture_fakewriter, 1721 NULL, fakewriter_tasks[i]); 1722 if (firsterr) 1723 goto unwind; 1724 } 1725 reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]), 1726 GFP_KERNEL); 1727 if (reader_tasks == NULL) { 1728 VERBOSE_TOROUT_ERRSTRING("out of memory"); 1729 firsterr = -ENOMEM; 1730 goto unwind; 1731 } 1732 for (i = 0; i < nrealreaders; i++) { 1733 firsterr = torture_create_kthread(rcu_torture_reader, NULL, 1734 reader_tasks[i]); 1735 if (firsterr) 1736 goto unwind; 1737 } 1738 if (stat_interval > 0) { 1739 firsterr = torture_create_kthread(rcu_torture_stats, NULL, 1740 stats_task); 1741 if (firsterr) 1742 goto unwind; 1743 } 1744 if (test_no_idle_hz) { 1745 firsterr = torture_shuffle_init(shuffle_interval * HZ); 1746 if (firsterr) 1747 goto unwind; 1748 } 1749 if (stutter < 0) 1750 stutter = 0; 1751 if (stutter) { 1752 firsterr = torture_stutter_init(stutter * HZ); 1753 if (firsterr) 1754 goto unwind; 1755 } 1756 if (fqs_duration < 0) 1757 fqs_duration = 0; 1758 if (fqs_duration) { 1759 /* Create the fqs thread */ 1760 firsterr = torture_create_kthread(rcu_torture_fqs, NULL, 1761 fqs_task); 1762 if (firsterr) 1763 goto unwind; 1764 } 1765 if (test_boost_interval < 1) 1766 test_boost_interval = 1; 1767 if (test_boost_duration < 2) 1768 test_boost_duration = 2; 1769 if ((test_boost == 1 && cur_ops->can_boost) || 1770 test_boost == 2) { 1771 1772 boost_starttime = jiffies + test_boost_interval * HZ; 1773 register_cpu_notifier(&rcutorture_cpu_nb); 1774 for_each_possible_cpu(i) { 1775 if (cpu_is_offline(i)) 1776 continue; /* Heuristic: CPU can go offline. */ 1777 firsterr = rcutorture_booster_init(i); 1778 if (firsterr) 1779 goto unwind; 1780 } 1781 } 1782 firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup); 1783 if (firsterr) 1784 goto unwind; 1785 firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ); 1786 if (firsterr) 1787 goto unwind; 1788 firsterr = rcu_torture_stall_init(); 1789 if (firsterr) 1790 goto unwind; 1791 firsterr = rcu_torture_barrier_init(); 1792 if (firsterr) 1793 goto unwind; 1794 if (object_debug) 1795 rcu_test_debug_objects(); 1796 if (cbflood_n_burst > 0) { 1797 /* Create the cbflood threads */ 1798 ncbflooders = (num_online_cpus() + 3) / 4; 1799 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task), 1800 GFP_KERNEL); 1801 if (!cbflood_task) { 1802 VERBOSE_TOROUT_ERRSTRING("out of memory"); 1803 firsterr = -ENOMEM; 1804 goto unwind; 1805 } 1806 for (i = 0; i < ncbflooders; i++) { 1807 firsterr = torture_create_kthread(rcu_torture_cbflood, 1808 NULL, 1809 cbflood_task[i]); 1810 if (firsterr) 1811 goto unwind; 1812 } 1813 } 1814 rcutorture_record_test_transition(); 1815 torture_init_end(); 1816 return 0; 1817 1818 unwind: 1819 torture_init_end(); 1820 rcu_torture_cleanup(); 1821 return firsterr; 1822 } 1823 1824 module_init(rcu_torture_init); 1825 module_exit(rcu_torture_cleanup); 1826