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  * Author: Paul E. McKenney <paulmck@us.ibm.com>
  21  *      Based on kernel/rcu/torture.c.
  22  */
  23 #include <linux/types.h>
  24 #include <linux/kernel.h>
  25 #include <linux/init.h>
  26 #include <linux/module.h>
  27 #include <linux/kthread.h>
  28 #include <linux/err.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/mutex.h>
  31 #include <linux/smp.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/sched.h>
  34 #include <linux/atomic.h>
  35 #include <linux/bitops.h>
  36 #include <linux/completion.h>
  37 #include <linux/moduleparam.h>
  38 #include <linux/percpu.h>
  39 #include <linux/notifier.h>
  40 #include <linux/reboot.h>
  41 #include <linux/freezer.h>
  42 #include <linux/cpu.h>
  43 #include <linux/delay.h>
  44 #include <linux/stat.h>
  45 #include <linux/slab.h>
  46 #include <linux/trace_clock.h>
  47 #include <asm/byteorder.h>
  48 #include <linux/torture.h>
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
  52
  53 torture_param(int, nwriters_stress, -1,
  54              "Number of write-locking stress-test threads");
  55 torture_param(int, nreaders_stress, -1,
  56              "Number of read-locking stress-test threads");
  57 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  58 torture_param(int, onoff_interval, 0,
  59              "Time between CPU hotplugs (s), 0=disable");
  60 torture_param(int, shuffle_interval, 3,
  61              "Number of jiffies between shuffles, 0=disable");
  62 torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
  63 torture_param(int, stat_interval, 60,
  64              "Number of seconds between stats printk()s");
  65 torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
  66 torture_param(bool, verbose, true,
  67              "Enable verbose debugging printk()s");
  68
  69 static char *torture_type = "spin_lock";
  70 module_param(torture_type, charp, 0444);
  71 MODULE_PARM_DESC(torture_type,
  72                  "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
  73
  74 static struct task_struct *stats_task;
  75 static struct task_struct **writer_tasks;
  76 static struct task_struct **reader_tasks;
  77
  78 static bool lock_is_write_held;
  79 static bool lock_is_read_held;
  80
  81 struct lock_stress_stats {
  82         long n_lock_fail;
  83         long n_lock_acquired;
  84 };
  85
  86 #if defined(MODULE)
  87 #define LOCKTORTURE_RUNNABLE_INIT 1
  88 #else
  89 #define LOCKTORTURE_RUNNABLE_INIT 0
  90 #endif
  91 int torture_runnable = LOCKTORTURE_RUNNABLE_INIT;
  92 module_param(torture_runnable, int, 0444);
  93 MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init");
  94
  95 /* Forward reference. */
  96 static void lock_torture_cleanup(void);
  97
  98 /*
  99  * Operations vector for selecting different types of tests.
 100  */
 101 struct lock_torture_ops {
 102         void (*init)(void);
 103         int (*writelock)(void);
 104         void (*write_delay)(struct torture_random_state *trsp);
 105         void (*writeunlock)(void);
 106         int (*readlock)(void);
 107         void (*read_delay)(struct torture_random_state *trsp);
 108         void (*readunlock)(void);
 109         unsigned long flags;
 110         const char *name;
 111 };
 112
 113 struct lock_torture_cxt {
 114         int nrealwriters_stress;
 115         int nrealreaders_stress;
 116         bool debug_lock;
 117         atomic_t n_lock_torture_errors;
 118         struct lock_torture_ops *cur_ops;
 119         struct lock_stress_stats *lwsa; /* writer statistics */
 120         struct lock_stress_stats *lrsa; /* reader statistics */
 121 };
 122 static struct lock_torture_cxt cxt = { 0, 0, false,
 123                                        ATOMIC_INIT(0),
 124                                        NULL, NULL};
 125 /*
 126  * Definitions for lock torture testing.
 127  */
 128
 129 static int torture_lock_busted_write_lock(void)
 130 {
 131         return 0;  /* BUGGY, do not use in real life!!! */
 132 }
 133
 134 static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
 135 {
 136         const unsigned long longdelay_us = 100;
 137
 138         /* We want a long delay occasionally to force massive contention.  */
 139         if (!(torture_random(trsp) %
 140               (cxt.nrealwriters_stress * 2000 * longdelay_us)))
 141                 mdelay(longdelay_us);
 142 #ifdef CONFIG_PREEMPT
 143         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 144                 preempt_schedule();  /* Allow test to be preempted. */
 145 #endif
 146 }
 147
 148 static void torture_lock_busted_write_unlock(void)
 149 {
 150           /* BUGGY, do not use in real life!!! */
 151 }
 152
 153 static struct lock_torture_ops lock_busted_ops = {
 154         .writelock      = torture_lock_busted_write_lock,
 155         .write_delay    = torture_lock_busted_write_delay,
 156         .writeunlock    = torture_lock_busted_write_unlock,
 157         .readlock       = NULL,
 158         .read_delay     = NULL,
 159         .readunlock     = NULL,
 160         .name           = "lock_busted"
 161 };
 162
 163 static DEFINE_SPINLOCK(torture_spinlock);
 164
 165 static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
 166 {
 167         spin_lock(&torture_spinlock);
 168         return 0;
 169 }
 170
 171 static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
 172 {
 173         const unsigned long shortdelay_us = 2;
 174         const unsigned long longdelay_us = 100;
 175
 176         /* We want a short delay mostly to emulate likely code, and
 177          * we want a long delay occasionally to force massive contention.
 178          */
 179         if (!(torture_random(trsp) %
 180               (cxt.nrealwriters_stress * 2000 * longdelay_us)))
 181                 mdelay(longdelay_us);
 182         if (!(torture_random(trsp) %
 183               (cxt.nrealwriters_stress * 2 * shortdelay_us)))
 184                 udelay(shortdelay_us);
 185 #ifdef CONFIG_PREEMPT
 186         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 187                 preempt_schedule();  /* Allow test to be preempted. */
 188 #endif
 189 }
 190
 191 static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
 192 {
 193         spin_unlock(&torture_spinlock);
 194 }
 195
 196 static struct lock_torture_ops spin_lock_ops = {
 197         .writelock      = torture_spin_lock_write_lock,
 198         .write_delay    = torture_spin_lock_write_delay,
 199         .writeunlock    = torture_spin_lock_write_unlock,
 200         .readlock       = NULL,
 201         .read_delay     = NULL,
 202         .readunlock     = NULL,
 203         .name           = "spin_lock"
 204 };
 205
 206 static int torture_spin_lock_write_lock_irq(void)
 207 __acquires(torture_spinlock_irq)
 208 {
 209         unsigned long flags;
 210
 211         spin_lock_irqsave(&torture_spinlock, flags);
 212         cxt.cur_ops->flags = flags;
 213         return 0;
 214 }
 215
 216 static void torture_lock_spin_write_unlock_irq(void)
 217 __releases(torture_spinlock)
 218 {
 219         spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
 220 }
 221
 222 static struct lock_torture_ops spin_lock_irq_ops = {
 223         .writelock      = torture_spin_lock_write_lock_irq,
 224         .write_delay    = torture_spin_lock_write_delay,
 225         .writeunlock    = torture_lock_spin_write_unlock_irq,
 226         .readlock       = NULL,
 227         .read_delay     = NULL,
 228         .readunlock     = NULL,
 229         .name           = "spin_lock_irq"
 230 };
 231
 232 static DEFINE_MUTEX(torture_mutex);
 233
 234 static int torture_mutex_lock(void) __acquires(torture_mutex)
 235 {
 236         mutex_lock(&torture_mutex);
 237         return 0;
 238 }
 239
 240 static void torture_mutex_delay(struct torture_random_state *trsp)
 241 {
 242         const unsigned long longdelay_ms = 100;
 243
 244         /* We want a long delay occasionally to force massive contention.  */
 245         if (!(torture_random(trsp) %
 246               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 247                 mdelay(longdelay_ms * 5);
 248         else
 249                 mdelay(longdelay_ms / 5);
 250 #ifdef CONFIG_PREEMPT
 251         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 252                 preempt_schedule();  /* Allow test to be preempted. */
 253 #endif
 254 }
 255
 256 static void torture_mutex_unlock(void) __releases(torture_mutex)
 257 {
 258         mutex_unlock(&torture_mutex);
 259 }
 260
 261 static struct lock_torture_ops mutex_lock_ops = {
 262         .writelock      = torture_mutex_lock,
 263         .write_delay    = torture_mutex_delay,
 264         .writeunlock    = torture_mutex_unlock,
 265         .readlock       = NULL,
 266         .read_delay     = NULL,
 267         .readunlock     = NULL,
 268         .name           = "mutex_lock"
 269 };
 270
 271 static DECLARE_RWSEM(torture_rwsem);
 272 static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
 273 {
 274         down_write(&torture_rwsem);
 275         return 0;
 276 }
 277
 278 static void torture_rwsem_write_delay(struct torture_random_state *trsp)
 279 {
 280         const unsigned long longdelay_ms = 100;
 281
 282         /* We want a long delay occasionally to force massive contention.  */
 283         if (!(torture_random(trsp) %
 284               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 285                 mdelay(longdelay_ms * 10);
 286         else
 287                 mdelay(longdelay_ms / 10);
 288 #ifdef CONFIG_PREEMPT
 289         if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 290                 preempt_schedule();  /* Allow test to be preempted. */
 291 #endif
 292 }
 293
 294 static void torture_rwsem_up_write(void) __releases(torture_rwsem)
 295 {
 296         up_write(&torture_rwsem);
 297 }
 298
 299 static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
 300 {
 301         down_read(&torture_rwsem);
 302         return 0;
 303 }
 304
 305 static void torture_rwsem_read_delay(struct torture_random_state *trsp)
 306 {
 307         const unsigned long longdelay_ms = 100;
 308
 309         /* We want a long delay occasionally to force massive contention.  */
 310         if (!(torture_random(trsp) %
 311               (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 312                 mdelay(longdelay_ms * 2);
 313         else
 314                 mdelay(longdelay_ms / 2);
 315 #ifdef CONFIG_PREEMPT
 316         if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
 317                 preempt_schedule();  /* Allow test to be preempted. */
 318 #endif
 319 }
 320
 321 static void torture_rwsem_up_read(void) __releases(torture_rwsem)
 322 {
 323         up_read(&torture_rwsem);
 324 }
 325
 326 static struct lock_torture_ops rwsem_lock_ops = {
 327         .writelock      = torture_rwsem_down_write,
 328         .write_delay    = torture_rwsem_write_delay,
 329         .writeunlock    = torture_rwsem_up_write,
 330         .readlock       = torture_rwsem_down_read,
 331         .read_delay     = torture_rwsem_read_delay,
 332         .readunlock     = torture_rwsem_up_read,
 333         .name           = "rwsem_lock"
 334 };
 335
 336 /*
 337  * Lock torture writer kthread.  Repeatedly acquires and releases
 338  * the lock, checking for duplicate acquisitions.
 339  */
 340 static int lock_torture_writer(void *arg)
 341 {
 342         struct lock_stress_stats *lwsp = arg;
 343         static DEFINE_TORTURE_RANDOM(rand);
 344
 345         VERBOSE_TOROUT_STRING("lock_torture_writer task started");
 346         set_user_nice(current, MAX_NICE);
 347
 348         do {
 349                 if ((torture_random(&rand) & 0xfffff) == 0)
 350                         schedule_timeout_uninterruptible(1);
 351                 cxt.cur_ops->writelock();
 352                 if (WARN_ON_ONCE(lock_is_write_held))
 353                         lwsp->n_lock_fail++;
 354                 lock_is_write_held = 1;
 355                 lwsp->n_lock_acquired++;
 356                 cxt.cur_ops->write_delay(&rand);
 357                 lock_is_write_held = 0;
 358                 cxt.cur_ops->writeunlock();
 359                 stutter_wait("lock_torture_writer");
 360         } while (!torture_must_stop());
 361         torture_kthread_stopping("lock_torture_writer");
 362         return 0;
 363 }
 364
 365 /*
 366  * Lock torture reader kthread.  Repeatedly acquires and releases
 367  * the reader lock.
 368  */
 369 static int lock_torture_reader(void *arg)
 370 {
 371         struct lock_stress_stats *lrsp = arg;
 372         static DEFINE_TORTURE_RANDOM(rand);
 373
 374         VERBOSE_TOROUT_STRING("lock_torture_reader task started");
 375         set_user_nice(current, MAX_NICE);
 376
 377         do {
 378                 if ((torture_random(&rand) & 0xfffff) == 0)
 379                         schedule_timeout_uninterruptible(1);
 380                 cxt.cur_ops->readlock();
 381                 lock_is_read_held = 1;
 382                 lrsp->n_lock_acquired++;
 383                 cxt.cur_ops->read_delay(&rand);
 384                 lock_is_read_held = 0;
 385                 cxt.cur_ops->readunlock();
 386                 stutter_wait("lock_torture_reader");
 387         } while (!torture_must_stop());
 388         torture_kthread_stopping("lock_torture_reader");
 389         return 0;
 390 }
 391
 392 /*
 393  * Create an lock-torture-statistics message in the specified buffer.
 394  */
 395 static void __torture_print_stats(char *page,
 396                                   struct lock_stress_stats *statp, bool write)
 397 {
 398         bool fail = 0;
 399         int i, n_stress;
 400         long max = 0;
 401         long min = statp[0].n_lock_acquired;
 402         long long sum = 0;
 403
 404         n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
 405         for (i = 0; i < n_stress; i++) {
 406                 if (statp[i].n_lock_fail)
 407                         fail = true;
 408                 sum += statp[i].n_lock_acquired;
 409                 if (max < statp[i].n_lock_fail)
 410                         max = statp[i].n_lock_fail;
 411                 if (min > statp[i].n_lock_fail)
 412                         min = statp[i].n_lock_fail;
 413         }
 414         page += sprintf(page,
 415                         "%s:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
 416                         write ? "Writes" : "Reads ",
 417                         sum, max, min, max / 2 > min ? "???" : "",
 418                         fail, fail ? "!!!" : "");
 419         if (fail)
 420                 atomic_inc(&cxt.n_lock_torture_errors);
 421 }
 422
 423 /*
 424  * Print torture statistics.  Caller must ensure that there is only one
 425  * call to this function at a given time!!!  This is normally accomplished
 426  * by relying on the module system to only have one copy of the module
 427  * loaded, and then by giving the lock_torture_stats kthread full control
 428  * (or the init/cleanup functions when lock_torture_stats thread is not
 429  * running).
 430  */
 431 static void lock_torture_stats_print(void)
 432 {
 433         int size = cxt.nrealwriters_stress * 200 + 8192;
 434         char *buf;
 435
 436         if (cxt.cur_ops->readlock)
 437                 size += cxt.nrealreaders_stress * 200 + 8192;
 438
 439         buf = kmalloc(size, GFP_KERNEL);
 440         if (!buf) {
 441                 pr_err("lock_torture_stats_print: Out of memory, need: %d",
 442                        size);
 443                 return;
 444         }
 445
 446         __torture_print_stats(buf, cxt.lwsa, true);
 447         pr_alert("%s", buf);
 448         kfree(buf);
 449
 450         if (cxt.cur_ops->readlock) {
 451                 buf = kmalloc(size, GFP_KERNEL);
 452                 if (!buf) {
 453                         pr_err("lock_torture_stats_print: Out of memory, need: %d",
 454                                size);
 455                         return;
 456                 }
 457
 458                 __torture_print_stats(buf, cxt.lrsa, false);
 459                 pr_alert("%s", buf);
 460                 kfree(buf);
 461         }
 462 }
 463
 464 /*
 465  * Periodically prints torture statistics, if periodic statistics printing
 466  * was specified via the stat_interval module parameter.
 467  *
 468  * No need to worry about fullstop here, since this one doesn't reference
 469  * volatile state or register callbacks.
 470  */
 471 static int lock_torture_stats(void *arg)
 472 {
 473         VERBOSE_TOROUT_STRING("lock_torture_stats task started");
 474         do {
 475                 schedule_timeout_interruptible(stat_interval * HZ);
 476                 lock_torture_stats_print();
 477                 torture_shutdown_absorb("lock_torture_stats");
 478         } while (!torture_must_stop());
 479         torture_kthread_stopping("lock_torture_stats");
 480         return 0;
 481 }
 482
 483 static inline void
 484 lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 485                                 const char *tag)
 486 {
 487         pr_alert("%s" TORTURE_FLAG
 488                  "--- %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",
 489                  torture_type, tag, cxt.debug_lock ? " [debug]": "",
 490                  cxt.nrealwriters_stress, cxt.nrealreaders_stress, stat_interval,
 491                  verbose, shuffle_interval, stutter, shutdown_secs,
 492                  onoff_interval, onoff_holdoff);
 493 }
 494
 495 static void lock_torture_cleanup(void)
 496 {
 497         int i;
 498
 499         if (torture_cleanup_begin())
 500                 return;
 501
 502         if (writer_tasks) {
 503                 for (i = 0; i < cxt.nrealwriters_stress; i++)
 504                         torture_stop_kthread(lock_torture_writer,
 505                                              writer_tasks[i]);
 506                 kfree(writer_tasks);
 507                 writer_tasks = NULL;
 508         }
 509
 510         if (reader_tasks) {
 511                 for (i = 0; i < cxt.nrealreaders_stress; i++)
 512                         torture_stop_kthread(lock_torture_reader,
 513                                              reader_tasks[i]);
 514                 kfree(reader_tasks);
 515                 reader_tasks = NULL;
 516         }
 517
 518         torture_stop_kthread(lock_torture_stats, stats_task);
 519         lock_torture_stats_print();  /* -After- the stats thread is stopped! */
 520
 521         if (atomic_read(&cxt.n_lock_torture_errors))
 522                 lock_torture_print_module_parms(cxt.cur_ops,
 523                                                 "End of test: FAILURE");
 524         else if (torture_onoff_failures())
 525                 lock_torture_print_module_parms(cxt.cur_ops,
 526                                                 "End of test: LOCK_HOTPLUG");
 527         else
 528                 lock_torture_print_module_parms(cxt.cur_ops,
 529                                                 "End of test: SUCCESS");
 530         torture_cleanup_end();
 531 }
 532
 533 static int __init lock_torture_init(void)
 534 {
 535         int i, j;
 536         int firsterr = 0;
 537         static struct lock_torture_ops *torture_ops[] = {
 538                 &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
 539                 &mutex_lock_ops, &rwsem_lock_ops,
 540         };
 541
 542         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
 543                 return -EBUSY;
 544
 545         /* Process args and tell the world that the torturer is on the job. */
 546         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 547                 cxt.cur_ops = torture_ops[i];
 548                 if (strcmp(torture_type, cxt.cur_ops->name) == 0)
 549                         break;
 550         }
 551         if (i == ARRAY_SIZE(torture_ops)) {
 552                 pr_alert("lock-torture: invalid torture type: \"%s\"\n",
 553                          torture_type);
 554                 pr_alert("lock-torture types:");
 555                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
 556                         pr_alert(" %s", torture_ops[i]->name);
 557                 pr_alert("\n");
 558                 torture_init_end();
 559                 return -EINVAL;
 560         }
 561         if (cxt.cur_ops->init)
 562                 cxt.cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 563
 564         if (nwriters_stress >= 0)
 565                 cxt.nrealwriters_stress = nwriters_stress;
 566         else
 567                 cxt.nrealwriters_stress = 2 * num_online_cpus();
 568
 569 #ifdef CONFIG_DEBUG_MUTEXES
 570         if (strncmp(torture_type, "mutex", 5) == 0)
 571                 cxt.debug_lock = true;
 572 #endif
 573 #ifdef CONFIG_DEBUG_SPINLOCK
 574         if (strncmp(torture_type, "spin", 4) == 0)
 575                 cxt.debug_lock = true;
 576 #endif
 577
 578         /* Initialize the statistics so that each run gets its own numbers. */
 579
 580         lock_is_write_held = 0;
 581         cxt.lwsa = kmalloc(sizeof(*cxt.lwsa) * cxt.nrealwriters_stress, GFP_KERNEL);
 582         if (cxt.lwsa == NULL) {
 583                 VERBOSE_TOROUT_STRING("cxt.lwsa: Out of memory");
 584                 firsterr = -ENOMEM;
 585                 goto unwind;
 586         }
 587         for (i = 0; i < cxt.nrealwriters_stress; i++) {
 588                 cxt.lwsa[i].n_lock_fail = 0;
 589                 cxt.lwsa[i].n_lock_acquired = 0;
 590         }
 591
 592         if (cxt.cur_ops->readlock) {
 593                 if (nreaders_stress >= 0)
 594                         cxt.nrealreaders_stress = nreaders_stress;
 595                 else {
 596                         /*
 597                          * By default distribute evenly the number of
 598                          * readers and writers. We still run the same number
 599                          * of threads as the writer-only locks default.
 600                          */
 601                         if (nwriters_stress < 0) /* user doesn't care */
 602                                 cxt.nrealwriters_stress = num_online_cpus();
 603                         cxt.nrealreaders_stress = cxt.nrealwriters_stress;
 604                 }
 605
 606                 lock_is_read_held = 0;
 607                 cxt.lrsa = kmalloc(sizeof(*cxt.lrsa) * cxt.nrealreaders_stress, GFP_KERNEL);
 608                 if (cxt.lrsa == NULL) {
 609                         VERBOSE_TOROUT_STRING("cxt.lrsa: Out of memory");
 610                         firsterr = -ENOMEM;
 611                         kfree(cxt.lwsa);
 612                         goto unwind;
 613                 }
 614
 615                 for (i = 0; i < cxt.nrealreaders_stress; i++) {
 616                         cxt.lrsa[i].n_lock_fail = 0;
 617                         cxt.lrsa[i].n_lock_acquired = 0;
 618                 }
 619         }
 620         lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
 621
 622         /* Prepare torture context. */
 623         if (onoff_interval > 0) {
 624                 firsterr = torture_onoff_init(onoff_holdoff * HZ,
 625                                               onoff_interval * HZ);
 626                 if (firsterr)
 627                         goto unwind;
 628         }
 629         if (shuffle_interval > 0) {
 630                 firsterr = torture_shuffle_init(shuffle_interval);
 631                 if (firsterr)
 632                         goto unwind;
 633         }
 634         if (shutdown_secs > 0) {
 635                 firsterr = torture_shutdown_init(shutdown_secs,
 636                                                  lock_torture_cleanup);
 637                 if (firsterr)
 638                         goto unwind;
 639         }
 640         if (stutter > 0) {
 641                 firsterr = torture_stutter_init(stutter);
 642                 if (firsterr)
 643                         goto unwind;
 644         }
 645
 646         writer_tasks = kzalloc(cxt.nrealwriters_stress * sizeof(writer_tasks[0]),
 647                                GFP_KERNEL);
 648         if (writer_tasks == NULL) {
 649                 VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
 650                 firsterr = -ENOMEM;
 651                 goto unwind;
 652         }
 653
 654         if (cxt.cur_ops->readlock) {
 655                 reader_tasks = kzalloc(cxt.nrealreaders_stress * sizeof(reader_tasks[0]),
 656                                        GFP_KERNEL);
 657                 if (reader_tasks == NULL) {
 658                         VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
 659                         firsterr = -ENOMEM;
 660                         goto unwind;
 661                 }
 662         }
 663
 664         /*
 665          * Create the kthreads and start torturing (oh, those poor little locks).
 666          *
 667          * TODO: Note that we interleave writers with readers, giving writers a
 668          * slight advantage, by creating its kthread first. This can be modified
 669          * for very specific needs, or even let the user choose the policy, if
 670          * ever wanted.
 671          */
 672         for (i = 0, j = 0; i < cxt.nrealwriters_stress ||
 673                     j < cxt.nrealreaders_stress; i++, j++) {
 674                 if (i >= cxt.nrealwriters_stress)
 675                         goto create_reader;
 676
 677                 /* Create writer. */
 678                 firsterr = torture_create_kthread(lock_torture_writer, &cxt.lwsa[i],
 679                                                   writer_tasks[i]);
 680                 if (firsterr)
 681                         goto unwind;
 682
 683         create_reader:
 684                 if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
 685                         continue;
 686                 /* Create reader. */
 687                 firsterr = torture_create_kthread(lock_torture_reader, &cxt.lrsa[j],
 688                                                   reader_tasks[j]);
 689                 if (firsterr)
 690                         goto unwind;
 691         }
 692         if (stat_interval > 0) {
 693                 firsterr = torture_create_kthread(lock_torture_stats, NULL,
 694                                                   stats_task);
 695                 if (firsterr)
 696                         goto unwind;
 697         }
 698         torture_init_end();
 699         return 0;
 700
 701 unwind:
 702         torture_init_end();
 703         lock_torture_cleanup();
 704         return firsterr;
 705 }
 706
 707 module_init(lock_torture_init);
 708 module_exit(lock_torture_cleanup);