module/splat/splat-mutex.c

   1 /*****************************************************************************\
   2  *  Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
   3  *  Copyright (C) 2007 The Regents of the University of California.
   4  *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
   5  *  Written by Brian Behlendorf <behlendorf1@llnl.gov>.
   6  *  UCRL-CODE-235197
   7  *
   8  *  This file is part of the SPL, Solaris Porting Layer.
   9  *  For details, see <http://github.com/behlendorf/spl/>.
  10  *
  11  *  The SPL is free software; you can redistribute it and/or modify it
  12  *  under the terms of the GNU General Public License as published by the
  13  *  Free Software Foundation; either version 2 of the License, or (at your
  14  *  option) any later version.
  15  *
  16  *  The SPL is distributed in the hope that it will be useful, but WITHOUT
  17  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19  *  for more details.
  20  *
  21  *  You should have received a copy of the GNU General Public License along
  22  *  with the SPL.  If not, see <http://www.gnu.org/licenses/>.
  23  *****************************************************************************
  24  *  Solaris Porting LAyer Tests (SPLAT) Mutex Tests.
  25 \*****************************************************************************/
  26
  27 #include <sys/mutex.h>
  28 #include <sys/taskq.h>
  29 #include "splat-internal.h"
  30
  31 #define SPLAT_MUTEX_NAME                "mutex"
  32 #define SPLAT_MUTEX_DESC                "Kernel Mutex Tests"
  33
  34 #define SPLAT_MUTEX_TEST1_ID            0x0401
  35 #define SPLAT_MUTEX_TEST1_NAME          "tryenter"
  36 #define SPLAT_MUTEX_TEST1_DESC          "Validate mutex_tryenter() correctness"
  37
  38 #define SPLAT_MUTEX_TEST2_ID            0x0402
  39 #define SPLAT_MUTEX_TEST2_NAME          "race"
  40 #define SPLAT_MUTEX_TEST2_DESC          "Many threads entering/exiting the mutex"
  41
  42 #define SPLAT_MUTEX_TEST3_ID            0x0403
  43 #define SPLAT_MUTEX_TEST3_NAME          "owned"
  44 #define SPLAT_MUTEX_TEST3_DESC          "Validate mutex_owned() correctness"
  45
  46 #define SPLAT_MUTEX_TEST4_ID            0x0404
  47 #define SPLAT_MUTEX_TEST4_NAME          "owner"
  48 #define SPLAT_MUTEX_TEST4_DESC          "Validate mutex_owner() correctness"
  49
  50 #define SPLAT_MUTEX_TEST_MAGIC          0x115599DDUL
  51 #define SPLAT_MUTEX_TEST_NAME           "mutex_test"
  52 #define SPLAT_MUTEX_TEST_TASKQ          "mutex_taskq"
  53 #define SPLAT_MUTEX_TEST_COUNT          128
  54
  55 typedef struct mutex_priv {
  56         unsigned long mp_magic;
  57         struct file *mp_file;
  58         kmutex_t mp_mtx;
  59         int mp_rc;
  60         int mp_rc2;
  61 } mutex_priv_t;
  62
  63 static void
  64 splat_mutex_test1_func(void *arg)
  65 {
  66         mutex_priv_t *mp = (mutex_priv_t *)arg;
  67         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
  68
  69         if (mutex_tryenter(&mp->mp_mtx)) {
  70                 mp->mp_rc = 0;
  71                 mutex_exit(&mp->mp_mtx);
  72         } else {
  73                 mp->mp_rc = -EBUSY;
  74         }
  75 }
  76
  77 static int
  78 splat_mutex_test1(struct file *file, void *arg)
  79 {
  80         mutex_priv_t *mp;
  81         taskq_t *tq;
  82         int id, rc = 0;
  83
  84         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
  85         if (mp == NULL)
  86                 return -ENOMEM;
  87
  88         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, 1, maxclsyspri,
  89                           50, INT_MAX, TASKQ_PREPOPULATE);
  90         if (tq == NULL) {
  91                 rc = -ENOMEM;
  92                 goto out2;
  93         }
  94
  95         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
  96         mp->mp_file = file;
  97         mutex_init(&mp->mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
  98         mutex_enter(&mp->mp_mtx);
  99
 100         /*
 101          * Schedule a task function which will try and acquire the mutex via
 102          * mutex_tryenter() while it's held.  This should fail and the task
 103          * function will indicate this status in the passed private data.
 104          */
 105         mp->mp_rc = -EINVAL;
 106         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 107         if (id == 0) {
 108                 mutex_exit(&mp->mp_mtx);
 109                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 110                              "taskq_dispatch() failed\n");
 111                 rc = -EINVAL;
 112                 goto out;
 113         }
 114
 115         taskq_wait_id(tq, id);
 116         mutex_exit(&mp->mp_mtx);
 117
 118         /* Task function successfully acquired mutex, very bad! */
 119         if (mp->mp_rc != -EBUSY) {
 120                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 121                              "mutex_trylock() incorrectly succeeded when "
 122                              "the mutex was held, %d/%d\n", id, mp->mp_rc);
 123                 rc = -EINVAL;
 124                 goto out;
 125         } else {
 126                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 127                              "mutex_trylock() correctly failed when "
 128                              "the mutex was held\n");
 129         }
 130
 131         /*
 132          * Schedule a task function which will try and acquire the mutex via
 133          * mutex_tryenter() while it is not held.  This should succeed and
 134          * can be verified by checking the private data.
 135          */
 136         mp->mp_rc = -EINVAL;
 137         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 138         if (id == 0) {
 139                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 140                              "taskq_dispatch() failed\n");
 141                 rc = -EINVAL;
 142                 goto out;
 143         }
 144
 145         taskq_wait_id(tq, id);
 146
 147         /* Task function failed to acquire mutex, very bad! */
 148         if (mp->mp_rc != 0) {
 149                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 150                              "mutex_trylock() incorrectly failed when "
 151                              "the mutex was not held, %d/%d\n", id, mp->mp_rc);
 152                 rc = -EINVAL;
 153         } else {
 154                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 155                              "mutex_trylock() correctly succeeded "
 156                              "when the mutex was not held\n");
 157         }
 158 out:
 159         taskq_destroy(tq);
 160         mutex_destroy(&(mp->mp_mtx));
 161 out2:
 162         kfree(mp);
 163         return rc;
 164 }
 165
 166 static void
 167 splat_mutex_test2_func(void *arg)
 168 {
 169         mutex_priv_t *mp = (mutex_priv_t *)arg;
 170         int rc;
 171         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 172
 173         /* Read the value before sleeping and write it after we wake up to
 174          * maximize the chance of a race if mutexs are not working properly */
 175         mutex_enter(&mp->mp_mtx);
 176         rc = mp->mp_rc;
 177         set_current_state(TASK_INTERRUPTIBLE);
 178         schedule_timeout(HZ / 100);  /* 1/100 of a second */
 179         VERIFY(mp->mp_rc == rc);
 180         mp->mp_rc = rc + 1;
 181         mutex_exit(&mp->mp_mtx);
 182 }
 183
 184 static int
 185 splat_mutex_test2(struct file *file, void *arg)
 186 {
 187         mutex_priv_t *mp;
 188         taskq_t *tq;
 189         int i, rc = 0;
 190
 191         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
 192         if (mp == NULL)
 193                 return -ENOMEM;
 194
 195         /* Create several threads allowing tasks to race with each other */
 196         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, num_online_cpus(),
 197                           maxclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
 198         if (tq == NULL) {
 199                 rc = -ENOMEM;
 200                 goto out;
 201         }
 202
 203         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 204         mp->mp_file = file;
 205         mutex_init(&(mp->mp_mtx), SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 206         mp->mp_rc = 0;
 207
 208         /*
 209          * Schedule N work items to the work queue each of which enters the
 210          * mutex, sleeps briefly, then exits the mutex.  On a multiprocessor
 211          * box these work items will be handled by all available CPUs.  The
 212          * task function checks to ensure the tracked shared variable is
 213          * always only incremented by one.  Additionally, the mutex itself
 214          * is instrumented such that if any two processors are in the
 215          * critical region at the same time the system will panic.  If the
 216          * mutex is implemented right this will never happy, that's a pass.
 217          */
 218         for (i = 0; i < SPLAT_MUTEX_TEST_COUNT; i++) {
 219                 if (!taskq_dispatch(tq, splat_mutex_test2_func, mp, TQ_SLEEP)) {
 220                         splat_vprint(file, SPLAT_MUTEX_TEST2_NAME,
 221                                      "Failed to queue task %d\n", i);
 222                         rc = -EINVAL;
 223                 }
 224         }
 225
 226         taskq_wait(tq);
 227
 228         if (mp->mp_rc == SPLAT_MUTEX_TEST_COUNT) {
 229                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 230                            "correctly entered/exited the mutex %d times\n",
 231                            num_online_cpus(), mp->mp_rc);
 232         } else {
 233                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 234                            "only processed %d/%d mutex work items\n",
 235                            num_online_cpus(),mp->mp_rc,SPLAT_MUTEX_TEST_COUNT);
 236                 rc = -EINVAL;
 237         }
 238
 239         taskq_destroy(tq);
 240         mutex_destroy(&(mp->mp_mtx));
 241 out:
 242         kfree(mp);
 243         return rc;
 244 }
 245
 246 static void
 247 splat_mutex_owned(void *priv)
 248 {
 249         mutex_priv_t *mp = (mutex_priv_t *)priv;
 250
 251         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 252         mp->mp_rc = mutex_owned(&mp->mp_mtx);
 253         mp->mp_rc2 = MUTEX_HELD(&mp->mp_mtx);
 254 }
 255
 256 static int
 257 splat_mutex_test3(struct file *file, void *arg)
 258 {
 259         mutex_priv_t mp;
 260         taskq_t *tq;
 261         int rc = 0;
 262
 263         mp.mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 264         mp.mp_file = file;
 265         mutex_init(&mp.mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 266
 267         if ((tq = taskq_create(SPLAT_MUTEX_TEST_NAME, 1, maxclsyspri,
 268                                50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 269                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Taskq '%s' "
 270                              "create failed\n", SPLAT_MUTEX_TEST3_NAME);
 271                 return -EINVAL;
 272         }
 273
 274         mutex_enter(&mp.mp_mtx);
 275
 276         /* Mutex should be owned by current */
 277         if (!mutex_owned(&mp.mp_mtx)) {
 278                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Unowned mutex "
 279                              "should be owned by pid %d\n", current->pid);
 280                 rc = -EINVAL;
 281                 goto out_exit;
 282         }
 283
 284         if (taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP) == 0) {
 285                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 286                              "dispatch function '%s' to taskq\n",
 287                              sym2str(splat_mutex_owned));
 288                 rc = -EINVAL;
 289                 goto out_exit;
 290         }
 291         taskq_wait(tq);
 292
 293         /* Mutex should not be owned which checked from a different thread */
 294         if (mp.mp_rc || mp.mp_rc2) {
 295                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 296                              "pid %d not by taskq\n", current->pid);
 297                 rc = -EINVAL;
 298                 goto out_exit;
 299         }
 300
 301         mutex_exit(&mp.mp_mtx);
 302
 303         /* Mutex should not be owned by current */
 304         if (mutex_owned(&mp.mp_mtx)) {
 305                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 306                              "pid %d it should be unowned\b", current->pid);
 307                 rc = -EINVAL;
 308                 goto out;
 309         }
 310
 311         if (taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP) == 0) {
 312                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 313                              "dispatch function '%s' to taskq\n",
 314                              sym2str(splat_mutex_owned));
 315                 rc = -EINVAL;
 316                 goto out;
 317         }
 318         taskq_wait(tq);
 319
 320         /* Mutex should be owned by no one */
 321         if (mp.mp_rc || mp.mp_rc2) {
 322                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 323                              "no one, %d/%d disagrees\n", mp.mp_rc, mp.mp_rc2);
 324                 rc = -EINVAL;
 325                 goto out;
 326         }
 327
 328         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 329                    "Correct mutex_owned() behavior\n");
 330         goto out;
 331 out_exit:
 332         mutex_exit(&mp.mp_mtx);
 333 out:
 334         mutex_destroy(&mp.mp_mtx);
 335         taskq_destroy(tq);
 336
 337         return rc;
 338 }
 339
 340 static int
 341 splat_mutex_test4(struct file *file, void *arg)
 342 {
 343         kmutex_t mtx;
 344         kthread_t *owner;
 345         int rc = 0;
 346
 347         mutex_init(&mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 348
 349         /*
 350          * Verify mutex owner is cleared after being dropped.  Depending
 351          * on how you build your kernel this behavior changes, ensure the
 352          * SPL mutex implementation is properly detecting this.
 353          */
 354         mutex_enter(&mtx);
 355         msleep(100);
 356         mutex_exit(&mtx);
 357         if (MUTEX_HELD(&mtx)) {
 358                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 359                            "not be held, bit is by %p\n", mutex_owner(&mtx));
 360                 rc = -EINVAL;
 361                 goto out;
 362         }
 363
 364         mutex_enter(&mtx);
 365
 366         /* Mutex should be owned by current */
 367         owner = mutex_owner(&mtx);
 368         if (current != owner) {
 369                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 370                            "be owned by pid %d but is owned by pid %d\n",
 371                            current->pid, owner ? owner->pid : -1);
 372                 rc = -EINVAL;
 373                 goto out;
 374         }
 375
 376         mutex_exit(&mtx);
 377
 378         /* Mutex should not be owned by any task */
 379         owner = mutex_owner(&mtx);
 380         if (owner) {
 381                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should not "
 382                            "be owned but is owned by pid %d\n", owner->pid);
 383                 rc = -EINVAL;
 384                 goto out;
 385         }
 386
 387         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 388                    "Correct mutex_owner() behavior\n");
 389 out:
 390         mutex_destroy(&mtx);
 391
 392         return rc;
 393 }
 394
 395 splat_subsystem_t *
 396 splat_mutex_init(void)
 397 {
 398         splat_subsystem_t *sub;
 399
 400         sub = kmalloc(sizeof(*sub), GFP_KERNEL);
 401         if (sub == NULL)
 402                 return NULL;
 403
 404         memset(sub, 0, sizeof(*sub));
 405         strncpy(sub->desc.name, SPLAT_MUTEX_NAME, SPLAT_NAME_SIZE);
 406         strncpy(sub->desc.desc, SPLAT_MUTEX_DESC, SPLAT_DESC_SIZE);
 407         INIT_LIST_HEAD(&sub->subsystem_list);
 408         INIT_LIST_HEAD(&sub->test_list);
 409         spin_lock_init(&sub->test_lock);
 410         sub->desc.id = SPLAT_SUBSYSTEM_MUTEX;
 411
 412         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST1_NAME, SPLAT_MUTEX_TEST1_DESC,
 413                       SPLAT_MUTEX_TEST1_ID, splat_mutex_test1);
 414         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST2_NAME, SPLAT_MUTEX_TEST2_DESC,
 415                       SPLAT_MUTEX_TEST2_ID, splat_mutex_test2);
 416         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST3_NAME, SPLAT_MUTEX_TEST3_DESC,
 417                       SPLAT_MUTEX_TEST3_ID, splat_mutex_test3);
 418         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST4_NAME, SPLAT_MUTEX_TEST4_DESC,
 419                       SPLAT_MUTEX_TEST4_ID, splat_mutex_test4);
 420
 421         return sub;
 422 }
 423
 424 void
 425 splat_mutex_fini(splat_subsystem_t *sub)
 426 {
 427         ASSERT(sub);
 428         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST4_ID);
 429         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST3_ID);
 430         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST2_ID);
 431         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST1_ID);
 432
 433         kfree(sub);
 434 }
 435
 436 int
 437 splat_mutex_id(void) {
 438         return SPLAT_SUBSYSTEM_MUTEX;
 439 }