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/smp.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/sched.h>
  33 #include <linux/atomic.h>
  34 #include <linux/bitops.h>
  35 #include <linux/completion.h>
  36 #include <linux/moduleparam.h>
  37 #include <linux/percpu.h>
  38 #include <linux/notifier.h>
  39 #include <linux/reboot.h>
  40 #include <linux/freezer.h>
  41 #include <linux/cpu.h>
  42 #include <linux/delay.h>
  43 #include <linux/stat.h>
  44 #include <linux/slab.h>
  45 #include <linux/trace_clock.h>
  46 #include <asm/byteorder.h>
  47 #include <linux/torture.h>
  48
  49 MODULE_LICENSE("GPL");
  50 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
  51
  52 torture_param(int, nwriters_stress, -1,
  53              "Number of write-locking stress-test threads");
  54 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  55 torture_param(int, onoff_interval, 0,
  56              "Time between CPU hotplugs (s), 0=disable");
  57 torture_param(int, shuffle_interval, 3,
  58              "Number of jiffies between shuffles, 0=disable");
  59 torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
  60 torture_param(int, stat_interval, 60,
  61              "Number of seconds between stats printk()s");
  62 torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
  63 torture_param(bool, verbose, true,
  64              "Enable verbose debugging printk()s");
  65
  66 static char *torture_type = "spin_lock";
  67 module_param(torture_type, charp, 0444);
  68 MODULE_PARM_DESC(torture_type,
  69                  "Type of lock to torture (spin_lock, spin_lock_irq, ...)");
  70
  71 static atomic_t n_lock_torture_errors;
  72
  73 static struct task_struct *stats_task;
  74 static struct task_struct **writer_tasks;
  75
  76 static int nrealwriters_stress;
  77 static bool lock_is_write_held;
  78
  79 struct lock_writer_stress_stats {
  80         long n_write_lock_fail;
  81         long n_write_lock_acquired;
  82 };
  83 static struct lock_writer_stress_stats *lwsa;
  84
  85 #if defined(MODULE)
  86 #define LOCKTORTURE_RUNNABLE_INIT 1
  87 #else
  88 #define LOCKTORTURE_RUNNABLE_INIT 0
  89 #endif
  90 int locktorture_runnable = LOCKTORTURE_RUNNABLE_INIT;
  91 module_param(locktorture_runnable, int, 0444);
  92 MODULE_PARM_DESC(locktorture_runnable, "Start locktorture at module init");
  93
  94 /* Forward reference. */
  95 static void lock_torture_cleanup(void);
  96
  97 /*
  98  * Operations vector for selecting different types of tests.
  99  */
 100 struct lock_torture_ops {
 101         void (*init)(void);
 102         int (*writelock)(void);
 103         void (*write_delay)(struct torture_random_state *trsp);
 104         void (*writeunlock)(void);
 105         unsigned long flags;
 106         const char *name;
 107 };
 108
 109 static struct lock_torture_ops *cur_ops;
 110
 111 /*
 112  * Definitions for lock torture testing.
 113  */
 114
 115 static int torture_lock_busted_write_lock(void)
 116 {
 117         return 0;  /* BUGGY, do not use in real life!!! */
 118 }
 119
 120 static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
 121 {
 122         const unsigned long longdelay_us = 100;
 123
 124         /* We want a long delay occasionally to force massive contention.  */
 125         if (!(torture_random(trsp) %
 126               (nrealwriters_stress * 2000 * longdelay_us)))
 127                 mdelay(longdelay_us);
 128 #ifdef CONFIG_PREEMPT
 129         if (!(torture_random(trsp) % (nrealwriters_stress * 20000)))
 130                 preempt_schedule();  /* Allow test to be preempted. */
 131 #endif
 132 }
 133
 134 static void torture_lock_busted_write_unlock(void)
 135 {
 136           /* BUGGY, do not use in real life!!! */
 137 }
 138
 139 static struct lock_torture_ops lock_busted_ops = {
 140         .writelock      = torture_lock_busted_write_lock,
 141         .write_delay    = torture_lock_busted_write_delay,
 142         .writeunlock    = torture_lock_busted_write_unlock,
 143         .name           = "lock_busted"
 144 };
 145
 146 static DEFINE_SPINLOCK(torture_spinlock);
 147
 148 static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
 149 {
 150         spin_lock(&torture_spinlock);
 151         return 0;
 152 }
 153
 154 static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
 155 {
 156         const unsigned long shortdelay_us = 2;
 157         const unsigned long longdelay_us = 100;
 158
 159         /* We want a short delay mostly to emulate likely code, and
 160          * we want a long delay occasionally to force massive contention.
 161          */
 162         if (!(torture_random(trsp) %
 163               (nrealwriters_stress * 2000 * longdelay_us)))
 164                 mdelay(longdelay_us);
 165         if (!(torture_random(trsp) %
 166               (nrealwriters_stress * 2 * shortdelay_us)))
 167                 udelay(shortdelay_us);
 168 #ifdef CONFIG_PREEMPT
 169         if (!(torture_random(trsp) % (nrealwriters_stress * 20000)))
 170                 preempt_schedule();  /* Allow test to be preempted. */
 171 #endif
 172 }
 173
 174 static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
 175 {
 176         spin_unlock(&torture_spinlock);
 177 }
 178
 179 static struct lock_torture_ops spin_lock_ops = {
 180         .writelock      = torture_spin_lock_write_lock,
 181         .write_delay    = torture_spin_lock_write_delay,
 182         .writeunlock    = torture_spin_lock_write_unlock,
 183         .name           = "spin_lock"
 184 };
 185
 186 static int torture_spin_lock_write_lock_irq(void)
 187 __acquires(torture_spinlock_irq)
 188 {
 189         unsigned long flags;
 190
 191         spin_lock_irqsave(&torture_spinlock, flags);
 192         cur_ops->flags = flags;
 193         return 0;
 194 }
 195
 196 static void torture_lock_spin_write_unlock_irq(void)
 197 __releases(torture_spinlock)
 198 {
 199         spin_unlock_irqrestore(&torture_spinlock, cur_ops->flags);
 200 }
 201
 202 static struct lock_torture_ops spin_lock_irq_ops = {
 203         .writelock      = torture_spin_lock_write_lock_irq,
 204         .write_delay    = torture_spin_lock_write_delay,
 205         .writeunlock    = torture_lock_spin_write_unlock_irq,
 206         .name           = "spin_lock_irq"
 207 };
 208
 209 /*
 210  * Lock torture writer kthread.  Repeatedly acquires and releases
 211  * the lock, checking for duplicate acquisitions.
 212  */
 213 static int lock_torture_writer(void *arg)
 214 {
 215         struct lock_writer_stress_stats *lwsp = arg;
 216         static DEFINE_TORTURE_RANDOM(rand);
 217
 218         VERBOSE_TOROUT_STRING("lock_torture_writer task started");
 219         set_user_nice(current, MAX_NICE);
 220
 221         do {
 222                 if ((torture_random(&rand) & 0xfffff) == 0)
 223                         schedule_timeout_uninterruptible(1);
 224                 cur_ops->writelock();
 225                 if (WARN_ON_ONCE(lock_is_write_held))
 226                         lwsp->n_write_lock_fail++;
 227                 lock_is_write_held = 1;
 228                 lwsp->n_write_lock_acquired++;
 229                 cur_ops->write_delay(&rand);
 230                 lock_is_write_held = 0;
 231                 cur_ops->writeunlock();
 232                 stutter_wait("lock_torture_writer");
 233         } while (!torture_must_stop());
 234         torture_kthread_stopping("lock_torture_writer");
 235         return 0;
 236 }
 237
 238 /*
 239  * Create an lock-torture-statistics message in the specified buffer.
 240  */
 241 static void lock_torture_printk(char *page)
 242 {
 243         bool fail = 0;
 244         int i;
 245         long max = 0;
 246         long min = lwsa[0].n_write_lock_acquired;
 247         long long sum = 0;
 248
 249         for (i = 0; i < nrealwriters_stress; i++) {
 250                 if (lwsa[i].n_write_lock_fail)
 251                         fail = true;
 252                 sum += lwsa[i].n_write_lock_acquired;
 253                 if (max < lwsa[i].n_write_lock_fail)
 254                         max = lwsa[i].n_write_lock_fail;
 255                 if (min > lwsa[i].n_write_lock_fail)
 256                         min = lwsa[i].n_write_lock_fail;
 257         }
 258         page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
 259         page += sprintf(page,
 260                         "Writes:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
 261                         sum, max, min, max / 2 > min ? "???" : "",
 262                         fail, fail ? "!!!" : "");
 263         if (fail)
 264                 atomic_inc(&n_lock_torture_errors);
 265 }
 266
 267 /*
 268  * Print torture statistics.  Caller must ensure that there is only one
 269  * call to this function at a given time!!!  This is normally accomplished
 270  * by relying on the module system to only have one copy of the module
 271  * loaded, and then by giving the lock_torture_stats kthread full control
 272  * (or the init/cleanup functions when lock_torture_stats thread is not
 273  * running).
 274  */
 275 static void lock_torture_stats_print(void)
 276 {
 277         int size = nrealwriters_stress * 200 + 8192;
 278         char *buf;
 279
 280         buf = kmalloc(size, GFP_KERNEL);
 281         if (!buf) {
 282                 pr_err("lock_torture_stats_print: Out of memory, need: %d",
 283                        size);
 284                 return;
 285         }
 286         lock_torture_printk(buf);
 287         pr_alert("%s", buf);
 288         kfree(buf);
 289 }
 290
 291 /*
 292  * Periodically prints torture statistics, if periodic statistics printing
 293  * was specified via the stat_interval module parameter.
 294  *
 295  * No need to worry about fullstop here, since this one doesn't reference
 296  * volatile state or register callbacks.
 297  */
 298 static int lock_torture_stats(void *arg)
 299 {
 300         VERBOSE_TOROUT_STRING("lock_torture_stats task started");
 301         do {
 302                 schedule_timeout_interruptible(stat_interval * HZ);
 303                 lock_torture_stats_print();
 304                 torture_shutdown_absorb("lock_torture_stats");
 305         } while (!torture_must_stop());
 306         torture_kthread_stopping("lock_torture_stats");
 307         return 0;
 308 }
 309
 310 static inline void
 311 lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 312                                 const char *tag)
 313 {
 314         pr_alert("%s" TORTURE_FLAG
 315                  "--- %s: nwriters_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
 316                  torture_type, tag, nrealwriters_stress, stat_interval, verbose,
 317                  shuffle_interval, stutter, shutdown_secs,
 318                  onoff_interval, onoff_holdoff);
 319 }
 320
 321 static void lock_torture_cleanup(void)
 322 {
 323         int i;
 324
 325         if (torture_cleanup())
 326                 return;
 327
 328         if (writer_tasks) {
 329                 for (i = 0; i < nrealwriters_stress; i++)
 330                         torture_stop_kthread(lock_torture_writer,
 331                                              writer_tasks[i]);
 332                 kfree(writer_tasks);
 333                 writer_tasks = NULL;
 334         }
 335
 336         torture_stop_kthread(lock_torture_stats, stats_task);
 337         lock_torture_stats_print();  /* -After- the stats thread is stopped! */
 338
 339         if (atomic_read(&n_lock_torture_errors))
 340                 lock_torture_print_module_parms(cur_ops,
 341                                                 "End of test: FAILURE");
 342         else if (torture_onoff_failures())
 343                 lock_torture_print_module_parms(cur_ops,
 344                                                 "End of test: LOCK_HOTPLUG");
 345         else
 346                 lock_torture_print_module_parms(cur_ops,
 347                                                 "End of test: SUCCESS");
 348 }
 349
 350 static int __init lock_torture_init(void)
 351 {
 352         int i;
 353         int firsterr = 0;
 354         static struct lock_torture_ops *torture_ops[] = {
 355                 &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
 356         };
 357
 358         if (!torture_init_begin(torture_type, verbose, &locktorture_runnable))
 359                 return -EBUSY;
 360
 361         /* Process args and tell the world that the torturer is on the job. */
 362         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 363                 cur_ops = torture_ops[i];
 364                 if (strcmp(torture_type, cur_ops->name) == 0)
 365                         break;
 366         }
 367         if (i == ARRAY_SIZE(torture_ops)) {
 368                 pr_alert("lock-torture: invalid torture type: \"%s\"\n",
 369                          torture_type);
 370                 pr_alert("lock-torture types:");
 371                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
 372                         pr_alert(" %s", torture_ops[i]->name);
 373                 pr_alert("\n");
 374                 torture_init_end();
 375                 return -EINVAL;
 376         }
 377         if (cur_ops->init)
 378                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 379
 380         if (nwriters_stress >= 0)
 381                 nrealwriters_stress = nwriters_stress;
 382         else
 383                 nrealwriters_stress = 2 * num_online_cpus();
 384         lock_torture_print_module_parms(cur_ops, "Start of test");
 385
 386         /* Initialize the statistics so that each run gets its own numbers. */
 387
 388         lock_is_write_held = 0;
 389         lwsa = kmalloc(sizeof(*lwsa) * nrealwriters_stress, GFP_KERNEL);
 390         if (lwsa == NULL) {
 391                 VERBOSE_TOROUT_STRING("lwsa: Out of memory");
 392                 firsterr = -ENOMEM;
 393                 goto unwind;
 394         }
 395         for (i = 0; i < nrealwriters_stress; i++) {
 396                 lwsa[i].n_write_lock_fail = 0;
 397                 lwsa[i].n_write_lock_acquired = 0;
 398         }
 399
 400         /* Start up the kthreads. */
 401
 402         if (onoff_interval > 0) {
 403                 firsterr = torture_onoff_init(onoff_holdoff * HZ,
 404                                               onoff_interval * HZ);
 405                 if (firsterr)
 406                         goto unwind;
 407         }
 408         if (shuffle_interval > 0) {
 409                 firsterr = torture_shuffle_init(shuffle_interval);
 410                 if (firsterr)
 411                         goto unwind;
 412         }
 413         if (shutdown_secs > 0) {
 414                 firsterr = torture_shutdown_init(shutdown_secs,
 415                                                  lock_torture_cleanup);
 416                 if (firsterr)
 417                         goto unwind;
 418         }
 419         if (stutter > 0) {
 420                 firsterr = torture_stutter_init(stutter);
 421                 if (firsterr)
 422                         goto unwind;
 423         }
 424
 425         writer_tasks = kzalloc(nrealwriters_stress * sizeof(writer_tasks[0]),
 426                                GFP_KERNEL);
 427         if (writer_tasks == NULL) {
 428                 VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
 429                 firsterr = -ENOMEM;
 430                 goto unwind;
 431         }
 432         for (i = 0; i < nrealwriters_stress; i++) {
 433                 firsterr = torture_create_kthread(lock_torture_writer, &lwsa[i],
 434                                                   writer_tasks[i]);
 435                 if (firsterr)
 436                         goto unwind;
 437         }
 438         if (stat_interval > 0) {
 439                 firsterr = torture_create_kthread(lock_torture_stats, NULL,
 440                                                   stats_task);
 441                 if (firsterr)
 442                         goto unwind;
 443         }
 444         torture_init_end();
 445         return 0;
 446
 447 unwind:
 448         torture_init_end();
 449         lock_torture_cleanup();
 450         return firsterr;
 451 }
 452
 453 module_init(lock_torture_init);
 454 module_exit(lock_torture_cleanup);