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) || defined(CONFIG_LOCK_TORTURE_TEST_RUNNABLE)
  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 boot");
  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, 19);
 220
 221         do {
 222                 schedule_timeout_uninterruptible(1);
 223                 cur_ops->writelock();
 224                 if (WARN_ON_ONCE(lock_is_write_held))
 225                         lwsp->n_write_lock_fail++;
 226                 lock_is_write_held = 1;
 227                 lwsp->n_write_lock_acquired++;
 228                 cur_ops->write_delay(&rand);
 229                 lock_is_write_held = 0;
 230                 cur_ops->writeunlock();
 231                 stutter_wait("lock_torture_writer");
 232         } while (!torture_must_stop());
 233         torture_kthread_stopping("lock_torture_writer");
 234         return 0;
 235 }
 236
 237 /*
 238  * Create an lock-torture-statistics message in the specified buffer.
 239  */
 240 static void lock_torture_printk(char *page)
 241 {
 242         bool fail = 0;
 243         int i;
 244         long max = 0;
 245         long min = lwsa[0].n_write_lock_acquired;
 246         long long sum = 0;
 247
 248         for (i = 0; i < nrealwriters_stress; i++) {
 249                 if (lwsa[i].n_write_lock_fail)
 250                         fail = true;
 251                 sum += lwsa[i].n_write_lock_acquired;
 252                 if (max < lwsa[i].n_write_lock_fail)
 253                         max = lwsa[i].n_write_lock_fail;
 254                 if (min > lwsa[i].n_write_lock_fail)
 255                         min = lwsa[i].n_write_lock_fail;
 256         }
 257         page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
 258         page += sprintf(page,
 259                         "Writes:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",
 260                         sum, max, min, max / 2 > min ? "???" : "",
 261                         fail, fail ? "!!!" : "");
 262         if (fail)
 263                 atomic_inc(&n_lock_torture_errors);
 264 }
 265
 266 /*
 267  * Print torture statistics.  Caller must ensure that there is only one
 268  * call to this function at a given time!!!  This is normally accomplished
 269  * by relying on the module system to only have one copy of the module
 270  * loaded, and then by giving the lock_torture_stats kthread full control
 271  * (or the init/cleanup functions when lock_torture_stats thread is not
 272  * running).
 273  */
 274 static void lock_torture_stats_print(void)
 275 {
 276         int size = nrealwriters_stress * 200 + 8192;
 277         char *buf;
 278
 279         buf = kmalloc(size, GFP_KERNEL);
 280         if (!buf) {
 281                 pr_err("lock_torture_stats_print: Out of memory, need: %d",
 282                        size);
 283                 return;
 284         }
 285         lock_torture_printk(buf);
 286         pr_alert("%s", buf);
 287         kfree(buf);
 288 }
 289
 290 /*
 291  * Periodically prints torture statistics, if periodic statistics printing
 292  * was specified via the stat_interval module parameter.
 293  *
 294  * No need to worry about fullstop here, since this one doesn't reference
 295  * volatile state or register callbacks.
 296  */
 297 static int lock_torture_stats(void *arg)
 298 {
 299         VERBOSE_TOROUT_STRING("lock_torture_stats task started");
 300         do {
 301                 schedule_timeout_interruptible(stat_interval * HZ);
 302                 lock_torture_stats_print();
 303                 torture_shutdown_absorb("lock_torture_stats");
 304         } while (!torture_must_stop());
 305         torture_kthread_stopping("lock_torture_stats");
 306         return 0;
 307 }
 308
 309 static inline void
 310 lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 311                                 const char *tag)
 312 {
 313         pr_alert("%s" TORTURE_FLAG
 314                  "--- %s: nwriters_stress=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
 315                  torture_type, tag, nrealwriters_stress, stat_interval, verbose,
 316                  shuffle_interval, stutter, shutdown_secs,
 317                  onoff_interval, onoff_holdoff);
 318 }
 319
 320 static void lock_torture_cleanup(void)
 321 {
 322         int i;
 323
 324         if (torture_cleanup())
 325                 return;
 326
 327         if (writer_tasks) {
 328                 for (i = 0; i < nrealwriters_stress; i++)
 329                         torture_stop_kthread(lock_torture_writer,
 330                                              writer_tasks[i]);
 331                 kfree(writer_tasks);
 332                 writer_tasks = NULL;
 333         }
 334
 335         torture_stop_kthread(lock_torture_stats, stats_task);
 336         lock_torture_stats_print();  /* -After- the stats thread is stopped! */
 337
 338         if (atomic_read(&n_lock_torture_errors))
 339                 lock_torture_print_module_parms(cur_ops,
 340                                                 "End of test: FAILURE");
 341         else if (torture_onoff_failures())
 342                 lock_torture_print_module_parms(cur_ops,
 343                                                 "End of test: LOCK_HOTPLUG");
 344         else
 345                 lock_torture_print_module_parms(cur_ops,
 346                                                 "End of test: SUCCESS");
 347 }
 348
 349 static int __init lock_torture_init(void)
 350 {
 351         int i;
 352         int firsterr = 0;
 353         static struct lock_torture_ops *torture_ops[] = {
 354                 &lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
 355         };
 356
 357         torture_init_begin(torture_type, verbose, &locktorture_runnable);
 358
 359         /* Process args and tell the world that the torturer is on the job. */
 360         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 361                 cur_ops = torture_ops[i];
 362                 if (strcmp(torture_type, cur_ops->name) == 0)
 363                         break;
 364         }
 365         if (i == ARRAY_SIZE(torture_ops)) {
 366                 pr_alert("lock-torture: invalid torture type: \"%s\"\n",
 367                          torture_type);
 368                 pr_alert("lock-torture types:");
 369                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
 370                         pr_alert(" %s", torture_ops[i]->name);
 371                 pr_alert("\n");
 372                 torture_init_end();
 373                 return -EINVAL;
 374         }
 375         if (cur_ops->init)
 376                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 377
 378         if (nwriters_stress >= 0)
 379                 nrealwriters_stress = nwriters_stress;
 380         else
 381                 nrealwriters_stress = 2 * num_online_cpus();
 382         lock_torture_print_module_parms(cur_ops, "Start of test");
 383
 384         /* Initialize the statistics so that each run gets its own numbers. */
 385
 386         lock_is_write_held = 0;
 387         lwsa = kmalloc(sizeof(*lwsa) * nrealwriters_stress, GFP_KERNEL);
 388         if (lwsa == NULL) {
 389                 VERBOSE_TOROUT_STRING("lwsa: Out of memory");
 390                 firsterr = -ENOMEM;
 391                 goto unwind;
 392         }
 393         for (i = 0; i < nrealwriters_stress; i++) {
 394                 lwsa[i].n_write_lock_fail = 0;
 395                 lwsa[i].n_write_lock_acquired = 0;
 396         }
 397
 398         /* Start up the kthreads. */
 399
 400         if (onoff_interval > 0) {
 401                 firsterr = torture_onoff_init(onoff_holdoff * HZ,
 402                                               onoff_interval * HZ);
 403                 if (firsterr)
 404                         goto unwind;
 405         }
 406         if (shuffle_interval > 0) {
 407                 firsterr = torture_shuffle_init(shuffle_interval);
 408                 if (firsterr)
 409                         goto unwind;
 410         }
 411         if (shutdown_secs > 0) {
 412                 firsterr = torture_shutdown_init(shutdown_secs,
 413                                                  lock_torture_cleanup);
 414                 if (firsterr)
 415                         goto unwind;
 416         }
 417         if (stutter > 0) {
 418                 firsterr = torture_stutter_init(stutter);
 419                 if (firsterr)
 420                         goto unwind;
 421         }
 422
 423         writer_tasks = kzalloc(nrealwriters_stress * sizeof(writer_tasks[0]),
 424                                GFP_KERNEL);
 425         if (writer_tasks == NULL) {
 426                 VERBOSE_TOROUT_ERRSTRING("writer_tasks: Out of memory");
 427                 firsterr = -ENOMEM;
 428                 goto unwind;
 429         }
 430         for (i = 0; i < nrealwriters_stress; i++) {
 431                 firsterr = torture_create_kthread(lock_torture_writer, &lwsa[i],
 432                                                   writer_tasks[i]);
 433                 if (firsterr)
 434                         goto unwind;
 435         }
 436         if (stat_interval > 0) {
 437                 firsterr = torture_create_kthread(lock_torture_stats, NULL,
 438                                                   stats_task);
 439                 if (firsterr)
 440                         goto unwind;
 441         }
 442         torture_init_end();
 443         return 0;
 444
 445 unwind:
 446         torture_init_end();
 447         lock_torture_cleanup();
 448         return firsterr;
 449 }
 450
 451 module_init(lock_torture_init);
 452 module_exit(lock_torture_cleanup);