kernel/locking/locktorture.c

   1 /*
   2  * Module-based torture test facility for locking
   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, 2014
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *          Davidlohr Bueso <dave@stgolabs.net>
  22  *      Based on kernel/rcu/torture.c.
  23  */
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/kthread.h>
  27 #include <linux/sched/rt.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/rwlock.h>
  30 #include <linux/mutex.h>
  31 #include <linux/rwsem.h>
  32 #include <linux/smp.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/sched.h>
  35 #include <uapi/linux/sched/types.h>
  36 #include <linux/rtmutex.h>
  37 #include <linux/atomic.h>
  38 #include <linux/moduleparam.h>
  39 #include <linux/delay.h>
  40 #include <linux/slab.h>
  41 #include <linux/percpu-rwsem.h>
  42 #include <linux/torture.h>
  43
  44 MODULE_LICENSE("GPL");
  45 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
  46
  47 torture_param(int, nwriters_stress, -1,
  48              "Number of write-locking stress-test threads");
  49 torture_param(int, nreaders_stress, -1,
  50              "Number of read-locking stress-test threads");
  51 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  52 torture_param(int, onoff_interval, 0,
  53              "Time between CPU hotplugs (s), 0=disable");
  54 torture_param(int, shuffle_interval, 3,
  55              "Number of jiffies between shuffles, 0=disable");
  56 torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
  57 torture_param(int, stat_interval, 60,
  58              "Number of seconds between stats printk()s");
  59 torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
  60 torture_param(bool, verbose, true,
  61              "Enable verbose debugging printk()s");
  62
  63 static char *torture_type = "spin_lock";
  64 module_param(torture_type, charp, 0444);
  65 MODULE_PARM_DESC(torture_type,
  66                  "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
  67
  68 static struct task_struct *stats_task;
  69 static struct task_struct **writer_tasks;
  70 static struct task_struct **reader_tasks;
  71
  72 static bool lock_is_write_held;
  73 static bool lock_is_read_held;
  74
  75 struct lock_stress_stats {
  76         long n_lock_fail;
  77         long n_lock_acquired;
  78 };
  79
  80 /* Forward reference. */
  81 static void lock_torture_cleanup(void);
  82
  83 /*
  84  * Operations vector for selecting different types of tests.
  85  */
  86 struct lock_torture_ops {
  87         void (*init)(void);
  88         int (*writelock)(void);
  89         void (*write_delay)(struct torture_random_state *trsp);
  90         void (*task_boost)(struct torture_random_state *trsp);
  91         void (*writeunlock)(void);
  92         int (*readlock)(void);
  93         void (*read_delay)(struct torture_random_state *trsp);
  94         void (*readunlock)(void);
  95
  96         unsigned long flags; /* for irq spinlocks */
  97         const char *name;
  98 };
  99
 100 struct lock_torture_cxt {
 101         int nrealwriters_stress;
 102         int nrealreaders_stress;
 103         bool debug_lock;
 104         atomic_t n_lock_torture_errors;
 105         struct lock_torture_ops *cur_ops;
 106         struct lock_stress_stats *lwsa; /* writer statistics */
 107         struct lock_stress_stats *lrsa; /* reader statistics */
 108 };
 109 static struct lock_torture_cxt cxt = { 0, 0, false,
 110                                        ATOMIC_INIT(0),
 111                                        NULL, NULL};
 112 /*
 113  * Definitions for lock torture testing.
 114  */
 115
 116 static int torture_lock_busted_write_lock(void)
 117 {
 118         return 0;  /* BUGGY, do not use in real life!!! */
 119 }
 120
 121 static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
 122 {
 123         const unsigned long longdelay_ms = 100;
 124
 125         /* We want a long delay occasionally to force massive contention.  */
 126         if (!(torture_random(trsp) %
 127               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 128                 mdelay(longdelay_ms);
 129         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 130                 torture_preempt_schedule();  /* Allow test to be preempted. */
 131 }
 132
 133 static void torture_lock_busted_write_unlock(void)
 134 {
 135           /* BUGGY, do not use in real life!!! */
 136 }
 137
 138 static void torture_boost_dummy(struct torture_random_state *trsp)
 139 {
 140         /* Only rtmutexes care about priority */
 141 }
 142
 143 static struct lock_torture_ops lock_busted_ops = {
 144         .writelock      = torture_lock_busted_write_lock,
 145         .write_delay    = torture_lock_busted_write_delay,
 146         .task_boost     = torture_boost_dummy,
 147         .writeunlock    = torture_lock_busted_write_unlock,
 148         .readlock       = NULL,
 149         .read_delay     = NULL,
 150         .readunlock     = NULL,
 151         .name           = "lock_busted"
 152 };
 153
 154 static DEFINE_SPINLOCK(torture_spinlock);
 155
 156 static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
 157 {
 158         spin_lock(&torture_spinlock);
 159         return 0;
 160 }
 161
 162 static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
 163 {
 164         const unsigned long shortdelay_us = 2;
 165         const unsigned long longdelay_ms = 100;
 166
 167         /* We want a short delay mostly to emulate likely code, and
 168          * we want a long delay occasionally to force massive contention.
 169          */
 170         if (!(torture_random(trsp) %
 171               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 172                 mdelay(longdelay_ms);
 173         if (!(torture_random(trsp) %
 174               (cxt.nrealwriters_stress * 2 * shortdelay_us)))
 175                 udelay(shortdelay_us);
 176         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 177                 torture_preempt_schedule();  /* Allow test to be preempted. */
 178 }
 179
 180 static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
 181 {
 182         spin_unlock(&torture_spinlock);
 183 }
 184
 185 static struct lock_torture_ops spin_lock_ops = {
 186         .writelock      = torture_spin_lock_write_lock,
 187         .write_delay    = torture_spin_lock_write_delay,
 188         .task_boost     = torture_boost_dummy,
 189         .writeunlock    = torture_spin_lock_write_unlock,
 190         .readlock       = NULL,
 191         .read_delay     = NULL,
 192         .readunlock     = NULL,
 193         .name           = "spin_lock"
 194 };
 195
 196 static int torture_spin_lock_write_lock_irq(void)
 197 __acquires(torture_spinlock)
 198 {
 199         unsigned long flags;
 200
 201         spin_lock_irqsave(&torture_spinlock, flags);
 202         cxt.cur_ops->flags = flags;
 203         return 0;
 204 }
 205
 206 static void torture_lock_spin_write_unlock_irq(void)
 207 __releases(torture_spinlock)
 208 {
 209         spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
 210 }
 211
 212 static struct lock_torture_ops spin_lock_irq_ops = {
 213         .writelock      = torture_spin_lock_write_lock_irq,
 214         .write_delay    = torture_spin_lock_write_delay,
 215         .task_boost     = torture_boost_dummy,
 216         .writeunlock    = torture_lock_spin_write_unlock_irq,
 217         .readlock       = NULL,
 218         .read_delay     = NULL,
 219         .readunlock     = NULL,
 220         .name           = "spin_lock_irq"
 221 };
 222
 223 static DEFINE_RWLOCK(torture_rwlock);
 224
 225 static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
 226 {
 227         write_lock(&torture_rwlock);
 228         return 0;
 229 }
 230
 231 static void torture_rwlock_write_delay(struct torture_random_state *trsp)
 232 {
 233         const unsigned long shortdelay_us = 2;
 234         const unsigned long longdelay_ms = 100;
 235
 236         /* We want a short delay mostly to emulate likely code, and
 237          * we want a long delay occasionally to force massive contention.
 238          */
 239         if (!(torture_random(trsp) %
 240               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 241                 mdelay(longdelay_ms);
 242         else
 243                 udelay(shortdelay_us);
 244 }
 245
 246 static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
 247 {
 248         write_unlock(&torture_rwlock);
 249 }
 250
 251 static int torture_rwlock_read_lock(void) __acquires(torture_rwlock)
 252 {
 253         read_lock(&torture_rwlock);
 254         return 0;
 255 }
 256
 257 static void torture_rwlock_read_delay(struct torture_random_state *trsp)
 258 {
 259         const unsigned long shortdelay_us = 10;
 260         const unsigned long longdelay_ms = 100;
 261
 262         /* We want a short delay mostly to emulate likely code, and
 263          * we want a long delay occasionally to force massive contention.
 264          */
 265         if (!(torture_random(trsp) %
 266               (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
 267                 mdelay(longdelay_ms);
 268         else
 269                 udelay(shortdelay_us);
 270 }
 271
 272 static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
 273 {
 274         read_unlock(&torture_rwlock);
 275 }
 276
 277 static struct lock_torture_ops rw_lock_ops = {
 278         .writelock      = torture_rwlock_write_lock,
 279         .write_delay    = torture_rwlock_write_delay,
 280         .task_boost     = torture_boost_dummy,
 281         .writeunlock    = torture_rwlock_write_unlock,
 282         .readlock       = torture_rwlock_read_lock,
 283         .read_delay     = torture_rwlock_read_delay,
 284         .readunlock     = torture_rwlock_read_unlock,
 285         .name           = "rw_lock"
 286 };
 287
 288 static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
 289 {
 290         unsigned long flags;
 291
 292         write_lock_irqsave(&torture_rwlock, flags);
 293         cxt.cur_ops->flags = flags;
 294         return 0;
 295 }
 296
 297 static void torture_rwlock_write_unlock_irq(void)
 298 __releases(torture_rwlock)
 299 {
 300         write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
 301 }
 302
 303 static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
 304 {
 305         unsigned long flags;
 306
 307         read_lock_irqsave(&torture_rwlock, flags);
 308         cxt.cur_ops->flags = flags;
 309         return 0;
 310 }
 311
 312 static void torture_rwlock_read_unlock_irq(void)
 313 __releases(torture_rwlock)
 314 {
 315         read_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
 316 }
 317
 318 static struct lock_torture_ops rw_lock_irq_ops = {
 319         .writelock      = torture_rwlock_write_lock_irq,
 320         .write_delay    = torture_rwlock_write_delay,
 321         .task_boost     = torture_boost_dummy,
 322         .writeunlock    = torture_rwlock_write_unlock_irq,
 323         .readlock       = torture_rwlock_read_lock_irq,
 324         .read_delay     = torture_rwlock_read_delay,
 325         .readunlock     = torture_rwlock_read_unlock_irq,
 326         .name           = "rw_lock_irq"
 327 };
 328
 329 static DEFINE_MUTEX(torture_mutex);
 330
 331 static int torture_mutex_lock(void) __acquires(torture_mutex)
 332 {
 333         mutex_lock(&torture_mutex);
 334         return 0;
 335 }
 336
 337 static void torture_mutex_delay(struct torture_random_state *trsp)
 338 {
 339         const unsigned long longdelay_ms = 100;
 340
 341         /* We want a long delay occasionally to force massive contention.  */
 342         if (!(torture_random(trsp) %
 343               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 344                 mdelay(longdelay_ms * 5);
 345         else
 346                 mdelay(longdelay_ms / 5);
 347         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 348                 torture_preempt_schedule();  /* Allow test to be preempted. */
 349 }
 350
 351 static void torture_mutex_unlock(void) __releases(torture_mutex)
 352 {
 353         mutex_unlock(&torture_mutex);
 354 }
 355
 356 static struct lock_torture_ops mutex_lock_ops = {
 357         .writelock      = torture_mutex_lock,
 358         .write_delay    = torture_mutex_delay,
 359         .task_boost     = torture_boost_dummy,
 360         .writeunlock    = torture_mutex_unlock,
 361         .readlock       = NULL,
 362         .read_delay     = NULL,
 363         .readunlock     = NULL,
 364         .name           = "mutex_lock"
 365 };
 366
 367 #include <linux/ww_mutex.h>
 368 static DEFINE_WW_CLASS(torture_ww_class);
 369 static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class);
 370 static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class);
 371 static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class);
 372
 373 static int torture_ww_mutex_lock(void)
 374 __acquires(torture_ww_mutex_0)
 375 __acquires(torture_ww_mutex_1)
 376 __acquires(torture_ww_mutex_2)
 377 {
 378         LIST_HEAD(list);
 379         struct reorder_lock {
 380                 struct list_head link;
 381                 struct ww_mutex *lock;
 382         } locks[3], *ll, *ln;
 383         struct ww_acquire_ctx ctx;
 384
 385         locks[0].lock = &torture_ww_mutex_0;
 386         list_add(&locks[0].link, &list);
 387
 388         locks[1].lock = &torture_ww_mutex_1;
 389         list_add(&locks[1].link, &list);
 390
 391         locks[2].lock = &torture_ww_mutex_2;
 392         list_add(&locks[2].link, &list);
 393
 394         ww_acquire_init(&ctx, &torture_ww_class);
 395
 396         list_for_each_entry(ll, &list, link) {
 397                 int err;
 398
 399                 err = ww_mutex_lock(ll->lock, &ctx);
 400                 if (!err)
 401                         continue;
 402
 403                 ln = ll;
 404                 list_for_each_entry_continue_reverse(ln, &list, link)
 405                         ww_mutex_unlock(ln->lock);
 406
 407                 if (err != -EDEADLK)
 408                         return err;
 409
 410                 ww_mutex_lock_slow(ll->lock, &ctx);
 411                 list_move(&ll->link, &list);
 412         }
 413
 414         ww_acquire_fini(&ctx);
 415         return 0;
 416 }
 417
 418 static void torture_ww_mutex_unlock(void)
 419 __releases(torture_ww_mutex_0)
 420 __releases(torture_ww_mutex_1)
 421 __releases(torture_ww_mutex_2)
 422 {
 423         ww_mutex_unlock(&torture_ww_mutex_0);
 424         ww_mutex_unlock(&torture_ww_mutex_1);
 425         ww_mutex_unlock(&torture_ww_mutex_2);
 426 }
 427
 428 static struct lock_torture_ops ww_mutex_lock_ops = {
 429         .writelock      = torture_ww_mutex_lock,
 430         .write_delay    = torture_mutex_delay,
 431         .task_boost     = torture_boost_dummy,
 432         .writeunlock    = torture_ww_mutex_unlock,
 433         .readlock       = NULL,
 434         .read_delay     = NULL,
 435         .readunlock     = NULL,
 436         .name           = "ww_mutex_lock"
 437 };
 438
 439 #ifdef CONFIG_RT_MUTEXES
 440 static DEFINE_RT_MUTEX(torture_rtmutex);
 441
 442 static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
 443 {
 444         rt_mutex_lock(&torture_rtmutex);
 445         return 0;
 446 }
 447
 448 static void torture_rtmutex_boost(struct torture_random_state *trsp)
 449 {
 450         int policy;
 451         struct sched_param param;
 452         const unsigned int factor = 50000; /* yes, quite arbitrary */
 453
 454         if (!rt_task(current)) {
 455                 /*
 456                  * Boost priority once every ~50k operations. When the
 457                  * task tries to take the lock, the rtmutex it will account
 458                  * for the new priority, and do any corresponding pi-dance.
 459                  */
 460                 if (trsp && !(torture_random(trsp) %
 461                               (cxt.nrealwriters_stress * factor))) {
 462                         policy = SCHED_FIFO;
 463                         param.sched_priority = MAX_RT_PRIO - 1;
 464                 } else /* common case, do nothing */
 465                         return;
 466         } else {
 467                 /*
 468                  * The task will remain boosted for another ~500k operations,
 469                  * then restored back to its original prio, and so forth.
 470                  *
 471                  * When @trsp is nil, we want to force-reset the task for
 472                  * stopping the kthread.
 473                  */
 474                 if (!trsp || !(torture_random(trsp) %
 475                                (cxt.nrealwriters_stress * factor * 2))) {
 476                         policy = SCHED_NORMAL;
 477                         param.sched_priority = 0;
 478                 } else /* common case, do nothing */
 479                         return;
 480         }
 481
 482         sched_setscheduler_nocheck(current, policy, &param);
 483 }
 484
 485 static void torture_rtmutex_delay(struct torture_random_state *trsp)
 486 {
 487         const unsigned long shortdelay_us = 2;
 488         const unsigned long longdelay_ms = 100;
 489
 490         /*
 491          * We want a short delay mostly to emulate likely code, and
 492          * we want a long delay occasionally to force massive contention.
 493          */
 494         if (!(torture_random(trsp) %
 495               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 496                 mdelay(longdelay_ms);
 497         if (!(torture_random(trsp) %
 498               (cxt.nrealwriters_stress * 2 * shortdelay_us)))
 499                 udelay(shortdelay_us);
 500         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 501                 torture_preempt_schedule();  /* Allow test to be preempted. */
 502 }
 503
 504 static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
 505 {
 506         rt_mutex_unlock(&torture_rtmutex);
 507 }
 508
 509 static struct lock_torture_ops rtmutex_lock_ops = {
 510         .writelock      = torture_rtmutex_lock,
 511         .write_delay    = torture_rtmutex_delay,
 512         .task_boost     = torture_rtmutex_boost,
 513         .writeunlock    = torture_rtmutex_unlock,
 514         .readlock       = NULL,
 515         .read_delay     = NULL,
 516         .readunlock     = NULL,
 517         .name           = "rtmutex_lock"
 518 };
 519 #endif
 520
 521 static DECLARE_RWSEM(torture_rwsem);
 522 static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
 523 {
 524         down_write(&torture_rwsem);
 525         return 0;
 526 }
 527
 528 static void torture_rwsem_write_delay(struct torture_random_state *trsp)
 529 {
 530         const unsigned long longdelay_ms = 100;
 531
 532         /* We want a long delay occasionally to force massive contention.  */
 533         if (!(torture_random(trsp) %
 534               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 535                 mdelay(longdelay_ms * 10);
 536         else
 537                 mdelay(longdelay_ms / 10);
 538         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 539                 torture_preempt_schedule();  /* Allow test to be preempted. */
 540 }
 541
 542 static void torture_rwsem_up_write(void) __releases(torture_rwsem)
 543 {
 544         up_write(&torture_rwsem);
 545 }
 546
 547 static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
 548 {
 549         down_read(&torture_rwsem);
 550         return 0;
 551 }
 552
 553 static void torture_rwsem_read_delay(struct torture_random_state *trsp)
 554 {
 555         const unsigned long longdelay_ms = 100;
 556
 557         /* We want a long delay occasionally to force massive contention.  */
 558         if (!(torture_random(trsp) %
 559               (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
 560                 mdelay(longdelay_ms * 2);
 561         else
 562                 mdelay(longdelay_ms / 2);
 563         if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
 564                 torture_preempt_schedule();  /* Allow test to be preempted. */
 565 }
 566
 567 static void torture_rwsem_up_read(void) __releases(torture_rwsem)
 568 {
 569         up_read(&torture_rwsem);
 570 }
 571
 572 static struct lock_torture_ops rwsem_lock_ops = {
 573         .writelock      = torture_rwsem_down_write,
 574         .write_delay    = torture_rwsem_write_delay,
 575         .task_boost     = torture_boost_dummy,
 576         .writeunlock    = torture_rwsem_up_write,
 577         .readlock       = torture_rwsem_down_read,
 578         .read_delay     = torture_rwsem_read_delay,
 579         .readunlock     = torture_rwsem_up_read,
 580         .name           = "rwsem_lock"
 581 };
 582
 583 #include <linux/percpu-rwsem.h>
 584 static struct percpu_rw_semaphore pcpu_rwsem;
 585
 586 void torture_percpu_rwsem_init(void)
 587 {
 588         BUG_ON(percpu_init_rwsem(&pcpu_rwsem));
 589 }
 590
 591 static int torture_percpu_rwsem_down_write(void) __acquires(pcpu_rwsem)
 592 {
 593         percpu_down_write(&pcpu_rwsem);
 594         return 0;
 595 }
 596
 597 static void torture_percpu_rwsem_up_write(void) __releases(pcpu_rwsem)
 598 {
 599         percpu_up_write(&pcpu_rwsem);
 600 }
 601
 602 static int torture_percpu_rwsem_down_read(void) __acquires(pcpu_rwsem)
 603 {
 604         percpu_down_read(&pcpu_rwsem);
 605         return 0;
 606 }
 607
 608 static void torture_percpu_rwsem_up_read(void) __releases(pcpu_rwsem)
 609 {
 610         percpu_up_read(&pcpu_rwsem);
 611 }
 612
 613 static struct lock_torture_ops percpu_rwsem_lock_ops = {
 614         .init           = torture_percpu_rwsem_init,
 615         .writelock      = torture_percpu_rwsem_down_write,
 616         .write_delay    = torture_rwsem_write_delay,
 617         .task_boost     = torture_boost_dummy,
 618         .writeunlock    = torture_percpu_rwsem_up_write,
 619         .readlock       = torture_percpu_rwsem_down_read,
 620         .read_delay     = torture_rwsem_read_delay,
 621         .readunlock     = torture_percpu_rwsem_up_read,
 622         .name           = "percpu_rwsem_lock"
 623 };
 624
 625 /*
 626  * Lock torture writer kthread.  Repeatedly acquires and releases
 627  * the lock, checking for duplicate acquisitions.
 628  */
 629 static int lock_torture_writer(void *arg)
 630 {
 631         struct lock_stress_stats *lwsp = arg;
 632         static DEFINE_TORTURE_RANDOM(rand);
 633
 634         VERBOSE_TOROUT_STRING("lock_torture_writer task started");
 635         set_user_nice(current, MAX_NICE);
 636
 637         do {
 638                 if ((torture_random(&rand) & 0xfffff) == 0)
 639                         schedule_timeout_uninterruptible(1);
 640
 641                 cxt.cur_ops->task_boost(&rand);
 642                 cxt.cur_ops->writelock();
 643                 if (WARN_ON_ONCE(lock_is_write_held))
 644                         lwsp->n_lock_fail++;
 645                 lock_is_write_held = 1;
 646                 if (WARN_ON_ONCE(lock_is_read_held))
 647                         lwsp->n_lock_fail++; /* rare, but... */
 648
 649                 lwsp->n_lock_acquired++;
 650                 cxt.cur_ops->write_delay(&rand);
 651                 lock_is_write_held = 0;
 652                 cxt.cur_ops->writeunlock();
 653
 654                 stutter_wait("lock_torture_writer");
 655         } while (!torture_must_stop());
 656
 657         cxt.cur_ops->task_boost(NULL); /* reset prio */
 658         torture_kthread_stopping("lock_torture_writer");
 659         return 0;
 660 }
 661
 662 /*
 663  * Lock torture reader kthread.  Repeatedly acquires and releases
 664  * the reader lock.
 665  */
 666 static int lock_torture_reader(void *arg)
 667 {
 668         struct lock_stress_stats *lrsp = arg;
 669         static DEFINE_TORTURE_RANDOM(rand);
 670
 671         VERBOSE_TOROUT_STRING("lock_torture_reader task started");
 672         set_user_nice(current, MAX_NICE);
 673
 674         do {
 675                 if ((torture_random(&rand) & 0xfffff) == 0)
 676                         schedule_timeout_uninterruptible(1);
 677
 678                 cxt.cur_ops->readlock();
 679                 lock_is_read_held = 1;
 680                 if (WARN_ON_ONCE(lock_is_write_held))
 681                         lrsp->n_lock_fail++; /* rare, but... */
 682
 683                 lrsp->n_lock_acquired++;
 684                 cxt.cur_ops->read_delay(&rand);
 685                 lock_is_read_held = 0;
 686                 cxt.cur_ops->readunlock();
 687
 688                 stutter_wait("lock_torture_reader");
 689         } while (!torture_must_stop());
 690         torture_kthread_stopping("lock_torture_reader");
 691         return 0;
 692 }
 693
 694 /*
 695  * Create an lock-torture-statistics message in the specified buffer.
 696  */
 697 static void __torture_print_stats(char *page,
 698                                   struct lock_stress_stats *statp, bool write)
 699 {
 700         bool fail = 0;
 701         int i, n_stress;
 702         long max = 0, min = statp ? statp[0].n_lock_acquired : 0;
 703         long long sum = 0;
 704
 705         n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
 706         for (i = 0; i < n_stress; i++) {
 707                 if (statp[i].n_lock_fail)
 708                         fail = true;
 709                 sum += statp[i].n_lock_acquired;
 710                 if (max < statp[i].n_lock_fail)
 711                         max = statp[i].n_lock_fail;
 712                 if (min > statp[i].n_lock_fail)
 713                         min = statp[i].n_lock_fail;
 714         }
 715         page += sprintf(page,
 716                         "%s:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
 717                         write ? "Writes" : "Reads ",
 718                         sum, max, min, max / 2 > min ? "???" : "",
 719                         fail, fail ? "!!!" : "");
 720         if (fail)
 721                 atomic_inc(&cxt.n_lock_torture_errors);
 722 }
 723
 724 /*
 725  * Print torture statistics.  Caller must ensure that there is only one
 726  * call to this function at a given time!!!  This is normally accomplished
 727  * by relying on the module system to only have one copy of the module
 728  * loaded, and then by giving the lock_torture_stats kthread full control
 729  * (or the init/cleanup functions when lock_torture_stats thread is not
 730  * running).
 731  */
 732 static void lock_torture_stats_print(void)
 733 {
 734         int size = cxt.nrealwriters_stress * 200 + 8192;
 735         char *buf;
 736
 737         if (cxt.cur_ops->readlock)
 738                 size += cxt.nrealreaders_stress * 200 + 8192;
 739
 740         buf = kmalloc(size, GFP_KERNEL);
 741         if (!buf) {
 742                 pr_err("lock_torture_stats_print: Out of memory, need: %d",
 743                        size);
 744                 return;
 745         }
 746
 747         __torture_print_stats(buf, cxt.lwsa, true);
 748         pr_alert("%s", buf);
 749         kfree(buf);
 750
 751         if (cxt.cur_ops->readlock) {
 752                 buf = kmalloc(size, GFP_KERNEL);
 753                 if (!buf) {
 754                         pr_err("lock_torture_stats_print: Out of memory, need: %d",
 755                                size);
 756                         return;
 757                 }
 758
 759                 __torture_print_stats(buf, cxt.lrsa, false);
 760                 pr_alert("%s", buf);
 761                 kfree(buf);
 762         }
 763 }
 764
 765 /*
 766  * Periodically prints torture statistics, if periodic statistics printing
 767  * was specified via the stat_interval module parameter.
 768  *
 769  * No need to worry about fullstop here, since this one doesn't reference
 770  * volatile state or register callbacks.
 771  */
 772 static int lock_torture_stats(void *arg)
 773 {
 774         VERBOSE_TOROUT_STRING("lock_torture_stats task started");
 775         do {
 776                 schedule_timeout_interruptible(stat_interval * HZ);
 777                 lock_torture_stats_print();
 778                 torture_shutdown_absorb("lock_torture_stats");
 779         } while (!torture_must_stop());
 780         torture_kthread_stopping("lock_torture_stats");
 781         return 0;
 782 }
 783
 784 static inline void
 785 lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 786                                 const char *tag)
 787 {
 788         pr_alert("%s" TORTURE_FLAG
 789                  "--- %s%s: nwriters_stress=%d nreaders_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
 790                  torture_type, tag, cxt.debug_lock ? " [debug]": "",
 791                  cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,
 792                  verbose, shuffle_interval, stutter, shutdown_secs,
 793                  onoff_interval, onoff_holdoff);
 794 }
 795
 796 static void lock_torture_cleanup(void)
 797 {
 798         int i;
 799
 800         if (torture_cleanup_begin())
 801                 return;
 802
 803         /*
 804          * Indicates early cleanup, meaning that the test has not run,
 805          * such as when passing bogus args when loading the module. As
 806          * such, only perform the underlying torture-specific cleanups,
 807          * and avoid anything related to locktorture.
 808          */
 809         if (!cxt.lwsa && !cxt.lrsa)
 810                 goto end;
 811
 812         if (writer_tasks) {
 813                 for (i = 0; i < cxt.nrealwriters_stress; i++)
 814                         torture_stop_kthread(lock_torture_writer,
 815                                              writer_tasks[i]);
 816                 kfree(writer_tasks);
 817                 writer_tasks = NULL;
 818         }
 819
 820         if (reader_tasks) {
 821                 for (i = 0; i < cxt.nrealreaders_stress; i++)
 822                         torture_stop_kthread(lock_torture_reader,
 823                                              reader_tasks[i]);
 824                 kfree(reader_tasks);
 825                 reader_tasks = NULL;
 826         }
 827
 828         torture_stop_kthread(lock_torture_stats, stats_task);
 829         lock_torture_stats_print();  /* -After- the stats thread is stopped! */
 830
 831         if (atomic_read(&cxt.n_lock_torture_errors))
 832                 lock_torture_print_module_parms(cxt.cur_ops,
 833                                                 "End of test: FAILURE");
 834         else if (torture_onoff_failures())
 835                 lock_torture_print_module_parms(cxt.cur_ops,
 836                                                 "End of test: LOCK_HOTPLUG");
 837         else
 838                 lock_torture_print_module_parms(cxt.cur_ops,
 839                                                 "End of test: SUCCESS");
 840
 841         kfree(cxt.lwsa);
 842         kfree(cxt.lrsa);
 843
 844 end:
 845         torture_cleanup_end();
 846 }
 847
 848 static int __init lock_torture_init(void)
 849 {
 850         int i, j;
 851         int firsterr = 0;
 852         static struct lock_torture_ops *torture_ops[] = {
 853                 &lock_busted_ops,
 854                 &spin_lock_ops, &spin_lock_irq_ops,
 855                 &rw_lock_ops, &rw_lock_irq_ops,
 856                 &mutex_lock_ops,
 857                 &ww_mutex_lock_ops,
 858 #ifdef CONFIG_RT_MUTEXES
 859                 &rtmutex_lock_ops,
 860 #endif
 861                 &rwsem_lock_ops,
 862                 &percpu_rwsem_lock_ops,
 863         };
 864
 865         if (!torture_init_begin(torture_type, verbose))
 866                 return -EBUSY;
 867
 868         /* Process args and tell the world that the torturer is on the job. */
 869         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 870                 cxt.cur_ops = torture_ops[i];
 871                 if (strcmp(torture_type, cxt.cur_ops->name) == 0)
 872                         break;
 873         }
 874         if (i == ARRAY_SIZE(torture_ops)) {
 875                 pr_alert("lock-torture: invalid torture type: \"%s\"\n",
 876                          torture_type);
 877                 pr_alert("lock-torture types:");
 878                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
 879                         pr_alert(" %s", torture_ops[i]->name);
 880                 pr_alert("\n");
 881                 firsterr = -EINVAL;
 882                 goto unwind;
 883         }
 884
 885         if (nwriters_stress == 0 && nreaders_stress == 0) {
 886                 pr_alert("lock-torture: must run at least one locking thread\n");
 887                 firsterr = -EINVAL;
 888                 goto unwind;
 889         }
 890
 891         if (cxt.cur_ops->init)
 892                 cxt.cur_ops->init();
 893
 894         if (nwriters_stress >= 0)
 895                 cxt.nrealwriters_stress = nwriters_stress;
 896         else
 897                 cxt.nrealwriters_stress = 2 * num_online_cpus();
 898
 899 #ifdef CONFIG_DEBUG_MUTEXES
 900         if (strncmp(torture_type, "mutex", 5) == 0)
 901                 cxt.debug_lock = true;
 902 #endif
 903 #ifdef CONFIG_DEBUG_RT_MUTEXES
 904         if (strncmp(torture_type, "rtmutex", 7) == 0)
 905                 cxt.debug_lock = true;
 906 #endif
 907 #ifdef CONFIG_DEBUG_SPINLOCK
 908         if ((strncmp(torture_type, "spin", 4) == 0) ||
 909             (strncmp(torture_type, "rw_lock", 7) == 0))
 910                 cxt.debug_lock = true;
 911 #endif
 912
 913         /* Initialize the statistics so that each run gets its own numbers. */
 914         if (nwriters_stress) {
 915                 lock_is_write_held = 0;
 916                 cxt.lwsa = kmalloc_array(cxt.nrealwriters_stress,
 917                                          sizeof(*cxt.lwsa),
 918                                          GFP_KERNEL);
 919                 if (cxt.lwsa == NULL) {
 920                         VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory");
 921                         firsterr = -ENOMEM;
 922                         goto unwind;
 923                 }
 924
 925                 for (i = 0; i < cxt.nrealwriters_stress; i++) {
 926                         cxt.lwsa[i].n_lock_fail = 0;
 927                         cxt.lwsa[i].n_lock_acquired = 0;
 928                 }
 929         }
 930
 931         if (cxt.cur_ops->readlock) {
 932                 if (nreaders_stress >= 0)
 933                         cxt.nrealreaders_stress = nreaders_stress;
 934                 else {
 935                         /*
 936                          * By default distribute evenly the number of
 937                          * readers and writers. We still run the same number
 938                          * of threads as the writer-only locks default.
 939                          */
 940                         if (nwriters_stress < 0) /* user doesn't care */
 941                                 cxt.nrealwriters_stress = num_online_cpus();
 942                         cxt.nrealreaders_stress = cxt.nrealwriters_stress;
 943                 }
 944
 945                 if (nreaders_stress) {
 946                         lock_is_read_held = 0;
 947                         cxt.lrsa = kmalloc_array(cxt.nrealreaders_stress,
 948                                                  sizeof(*cxt.lrsa),
 949                                                  GFP_KERNEL);
 950                         if (cxt.lrsa == NULL) {
 951                                 VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
 952                                 firsterr = -ENOMEM;
 953                                 kfree(cxt.lwsa);
 954                                 cxt.lwsa = NULL;
 955                                 goto unwind;
 956                         }
 957
 958                         for (i = 0; i < cxt.nrealreaders_stress; i++) {
 959                                 cxt.lrsa[i].n_lock_fail = 0;
 960                                 cxt.lrsa[i].n_lock_acquired = 0;
 961                         }
 962                 }
 963         }
 964
 965         lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
 966
 967         /* Prepare torture context. */
 968         if (onoff_interval > 0) {
 969                 firsterr = torture_onoff_init(onoff_holdoff * HZ,
 970                                               onoff_interval * HZ);
 971                 if (firsterr)
 972                         goto unwind;
 973         }
 974         if (shuffle_interval > 0) {
 975                 firsterr = torture_shuffle_init(shuffle_interval);
 976                 if (firsterr)
 977                         goto unwind;
 978         }
 979         if (shutdown_secs > 0) {
 980                 firsterr = torture_shutdown_init(shutdown_secs,
 981                                                  lock_torture_cleanup);
 982                 if (firsterr)
 983                         goto unwind;
 984         }
 985         if (stutter > 0) {
 986                 firsterr = torture_stutter_init(stutter);
 987                 if (firsterr)
 988                         goto unwind;
 989         }
 990
 991         if (nwriters_stress) {
 992                 writer_tasks = kcalloc(cxt.nrealwriters_stress,
 993                                        sizeof(writer_tasks[0]),
 994                                        GFP_KERNEL);
 995                 if (writer_tasks == NULL) {
 996                         VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
 997                         firsterr = -ENOMEM;
 998                         goto unwind;
 999                 }
1000         }
1001
1002         if (cxt.cur_ops->readlock) {
1003                 reader_tasks = kcalloc(cxt.nrealreaders_stress,
1004                                        sizeof(reader_tasks[0]),
1005                                        GFP_KERNEL);
1006                 if (reader_tasks == NULL) {
1007                         VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
1008                         kfree(writer_tasks);
1009                         writer_tasks = NULL;
1010                         firsterr = -ENOMEM;
1011                         goto unwind;
1012                 }
1013         }
1014
1015         /*
1016          * Create the kthreads and start torturing (oh, those poor little locks).
1017          *
1018          * TODO: Note that we interleave writers with readers, giving writers a
1019          * slight advantage, by creating its kthread first. This can be modified
1020          * for very specific needs, or even let the user choose the policy, if
1021          * ever wanted.
1022          */
1023         for (i = 0, j = 0; i < cxt.nrealwriters_stress ||
1024                     j < cxt.nrealreaders_stress; i++, j++) {
1025                 if (i >= cxt.nrealwriters_stress)
1026                         goto create_reader;
1027
1028                 /* Create writer. */
1029                 firsterr = torture_create_kthread(lock_torture_writer, &cxt.lwsa[i],
1030                                                   writer_tasks[i]);
1031                 if (firsterr)
1032                         goto unwind;
1033
1034         create_reader:
1035                 if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
1036                         continue;
1037                 /* Create reader. */
1038                 firsterr = torture_create_kthread(lock_torture_reader, &cxt.lrsa[j],
1039                                                   reader_tasks[j]);
1040                 if (firsterr)
1041                         goto unwind;
1042         }
1043         if (stat_interval > 0) {
1044                 firsterr = torture_create_kthread(lock_torture_stats, NULL,
1045                                                   stats_task);
1046                 if (firsterr)
1047                         goto unwind;
1048         }
1049         torture_init_end();
1050         return 0;
1051
1052 unwind:
1053         torture_init_end();
1054         lock_torture_cleanup();
1055         return firsterr;
1056 }
1057
1058 module_init(lock_torture_init);
1059 module_exit(lock_torture_cleanup);