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://zfsonlinux.org/>.
  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 <linux/delay.h>
  30 #include <linux/mm_compat.h>
  31 #include "splat-internal.h"
  32
  33 #define SPLAT_MUTEX_NAME                "mutex"
  34 #define SPLAT_MUTEX_DESC                "Kernel Mutex Tests"
  35
  36 #define SPLAT_MUTEX_TEST1_ID            0x0401
  37 #define SPLAT_MUTEX_TEST1_NAME          "tryenter"
  38 #define SPLAT_MUTEX_TEST1_DESC          "Validate mutex_tryenter() correctness"
  39
  40 #define SPLAT_MUTEX_TEST2_ID            0x0402
  41 #define SPLAT_MUTEX_TEST2_NAME          "race"
  42 #define SPLAT_MUTEX_TEST2_DESC          "Many threads entering/exiting the mutex"
  43
  44 #define SPLAT_MUTEX_TEST3_ID            0x0403
  45 #define SPLAT_MUTEX_TEST3_NAME          "owned"
  46 #define SPLAT_MUTEX_TEST3_DESC          "Validate mutex_owned() correctness"
  47
  48 #define SPLAT_MUTEX_TEST4_ID            0x0404
  49 #define SPLAT_MUTEX_TEST4_NAME          "owner"
  50 #define SPLAT_MUTEX_TEST4_DESC          "Validate mutex_owner() correctness"
  51
  52 #define SPLAT_MUTEX_TEST_MAGIC          0x115599DDUL
  53 #define SPLAT_MUTEX_TEST_NAME           "mutex_test"
  54 #define SPLAT_MUTEX_TEST_TASKQ          "mutex_taskq"
  55 #define SPLAT_MUTEX_TEST_COUNT          128
  56
  57 typedef struct mutex_priv {
  58         unsigned long mp_magic;
  59         struct file *mp_file;
  60         kmutex_t mp_mtx;
  61         int mp_rc;
  62         int mp_rc2;
  63 } mutex_priv_t;
  64
  65 static void
  66 splat_mutex_test1_func(void *arg)
  67 {
  68         mutex_priv_t *mp = (mutex_priv_t *)arg;
  69         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
  70
  71         if (mutex_tryenter(&mp->mp_mtx)) {
  72                 mp->mp_rc = 0;
  73                 mutex_exit(&mp->mp_mtx);
  74         } else {
  75                 mp->mp_rc = -EBUSY;
  76         }
  77 }
  78
  79 static int
  80 splat_mutex_test1(struct file *file, void *arg)
  81 {
  82         mutex_priv_t *mp;
  83         taskq_t *tq;
  84         int id, rc = 0;
  85
  86         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
  87         if (mp == NULL)
  88                 return -ENOMEM;
  89
  90         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, 1, defclsyspri,
  91                           50, INT_MAX, TASKQ_PREPOPULATE);
  92         if (tq == NULL) {
  93                 rc = -ENOMEM;
  94                 goto out2;
  95         }
  96
  97         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
  98         mp->mp_file = file;
  99         mutex_init(&mp->mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 100         mutex_enter(&mp->mp_mtx);
 101
 102         /*
 103          * Schedule a task function which will try and acquire the mutex via
 104          * mutex_tryenter() while it's held.  This should fail and the task
 105          * function will indicate this status in the passed private data.
 106          */
 107         mp->mp_rc = -EINVAL;
 108         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 109         if (id == 0) {
 110                 mutex_exit(&mp->mp_mtx);
 111                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 112                              "taskq_dispatch() failed\n");
 113                 rc = -EINVAL;
 114                 goto out;
 115         }
 116
 117         taskq_wait_id(tq, id);
 118         mutex_exit(&mp->mp_mtx);
 119
 120         /* Task function successfully acquired mutex, very bad! */
 121         if (mp->mp_rc != -EBUSY) {
 122                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 123                              "mutex_trylock() incorrectly succeeded when "
 124                              "the mutex was held, %d/%d\n", id, mp->mp_rc);
 125                 rc = -EINVAL;
 126                 goto out;
 127         } else {
 128                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 129                              "mutex_trylock() correctly failed when "
 130                              "the mutex was held\n");
 131         }
 132
 133         /*
 134          * Schedule a task function which will try and acquire the mutex via
 135          * mutex_tryenter() while it is not held.  This should succeed and
 136          * can be verified by checking the private data.
 137          */
 138         mp->mp_rc = -EINVAL;
 139         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 140         if (id == 0) {
 141                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 142                              "taskq_dispatch() failed\n");
 143                 rc = -EINVAL;
 144                 goto out;
 145         }
 146
 147         taskq_wait_id(tq, id);
 148
 149         /* Task function failed to acquire mutex, very bad! */
 150         if (mp->mp_rc != 0) {
 151                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 152                              "mutex_trylock() incorrectly failed when "
 153                              "the mutex was not held, %d/%d\n", id, mp->mp_rc);
 154                 rc = -EINVAL;
 155         } else {
 156                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 157                              "mutex_trylock() correctly succeeded "
 158                              "when the mutex was not held\n");
 159         }
 160 out:
 161         taskq_destroy(tq);
 162         mutex_destroy(&(mp->mp_mtx));
 163 out2:
 164         kfree(mp);
 165         return rc;
 166 }
 167
 168 static void
 169 splat_mutex_test2_func(void *arg)
 170 {
 171         mutex_priv_t *mp = (mutex_priv_t *)arg;
 172         int rc;
 173         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 174
 175         /* Read the value before sleeping and write it after we wake up to
 176          * maximize the chance of a race if mutexs are not working properly */
 177         mutex_enter(&mp->mp_mtx);
 178         rc = mp->mp_rc;
 179         set_current_state(TASK_INTERRUPTIBLE);
 180         schedule_timeout(HZ / 100);  /* 1/100 of a second */
 181         VERIFY(mp->mp_rc == rc);
 182         mp->mp_rc = rc + 1;
 183         mutex_exit(&mp->mp_mtx);
 184 }
 185
 186 static int
 187 splat_mutex_test2(struct file *file, void *arg)
 188 {
 189         mutex_priv_t *mp;
 190         taskq_t *tq;
 191         int i, rc = 0;
 192
 193         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
 194         if (mp == NULL)
 195                 return -ENOMEM;
 196
 197         /* Create several threads allowing tasks to race with each other */
 198         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, num_online_cpus(),
 199                           defclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
 200         if (tq == NULL) {
 201                 rc = -ENOMEM;
 202                 goto out;
 203         }
 204
 205         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 206         mp->mp_file = file;
 207         mutex_init(&(mp->mp_mtx), SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 208         mp->mp_rc = 0;
 209
 210         /*
 211          * Schedule N work items to the work queue each of which enters the
 212          * mutex, sleeps briefly, then exits the mutex.  On a multiprocessor
 213          * box these work items will be handled by all available CPUs.  The
 214          * task function checks to ensure the tracked shared variable is
 215          * always only incremented by one.  Additionally, the mutex itself
 216          * is instrumented such that if any two processors are in the
 217          * critical region at the same time the system will panic.  If the
 218          * mutex is implemented right this will never happy, that's a pass.
 219          */
 220         for (i = 0; i < SPLAT_MUTEX_TEST_COUNT; i++) {
 221                 if (!taskq_dispatch(tq, splat_mutex_test2_func, mp, TQ_SLEEP)) {
 222                         splat_vprint(file, SPLAT_MUTEX_TEST2_NAME,
 223                                      "Failed to queue task %d\n", i);
 224                         rc = -EINVAL;
 225                 }
 226         }
 227
 228         taskq_wait(tq);
 229
 230         if (mp->mp_rc == SPLAT_MUTEX_TEST_COUNT) {
 231                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 232                            "correctly entered/exited the mutex %d times\n",
 233                            num_online_cpus(), mp->mp_rc);
 234         } else {
 235                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 236                            "only processed %d/%d mutex work items\n",
 237                            num_online_cpus(),mp->mp_rc,SPLAT_MUTEX_TEST_COUNT);
 238                 rc = -EINVAL;
 239         }
 240
 241         taskq_destroy(tq);
 242         mutex_destroy(&(mp->mp_mtx));
 243 out:
 244         kfree(mp);
 245         return rc;
 246 }
 247
 248 static void
 249 splat_mutex_owned(void *priv)
 250 {
 251         mutex_priv_t *mp = (mutex_priv_t *)priv;
 252
 253         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 254         mp->mp_rc = mutex_owned(&mp->mp_mtx);
 255         mp->mp_rc2 = MUTEX_HELD(&mp->mp_mtx);
 256 }
 257
 258 static int
 259 splat_mutex_test3(struct file *file, void *arg)
 260 {
 261         mutex_priv_t mp;
 262         taskq_t *tq;
 263         int rc = 0;
 264
 265         mp.mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 266         mp.mp_file = file;
 267         mutex_init(&mp.mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 268
 269         if ((tq = taskq_create(SPLAT_MUTEX_TEST_NAME, 1, defclsyspri,
 270                                50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 271                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Taskq '%s' "
 272                              "create failed\n", SPLAT_MUTEX_TEST3_NAME);
 273                 return -EINVAL;
 274         }
 275
 276         mutex_enter(&mp.mp_mtx);
 277
 278         /* Mutex should be owned by current */
 279         if (!mutex_owned(&mp.mp_mtx)) {
 280                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Unowned mutex "
 281                              "should be owned by pid %d\n", current->pid);
 282                 rc = -EINVAL;
 283                 goto out_exit;
 284         }
 285
 286         if (taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP) == 0) {
 287                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 288                              "dispatch function '%s' to taskq\n",
 289                              sym2str(splat_mutex_owned));
 290                 rc = -EINVAL;
 291                 goto out_exit;
 292         }
 293         taskq_wait(tq);
 294
 295         /* Mutex should not be owned which checked from a different thread */
 296         if (mp.mp_rc || mp.mp_rc2) {
 297                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 298                              "pid %d not by taskq\n", current->pid);
 299                 rc = -EINVAL;
 300                 goto out_exit;
 301         }
 302
 303         mutex_exit(&mp.mp_mtx);
 304
 305         /* Mutex should not be owned by current */
 306         if (mutex_owned(&mp.mp_mtx)) {
 307                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 308                              "pid %d it should be unowned\b", current->pid);
 309                 rc = -EINVAL;
 310                 goto out;
 311         }
 312
 313         if (taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP) == 0) {
 314                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 315                              "dispatch function '%s' to taskq\n",
 316                              sym2str(splat_mutex_owned));
 317                 rc = -EINVAL;
 318                 goto out;
 319         }
 320         taskq_wait(tq);
 321
 322         /* Mutex should be owned by no one */
 323         if (mp.mp_rc || mp.mp_rc2) {
 324                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 325                              "no one, %d/%d disagrees\n", mp.mp_rc, mp.mp_rc2);
 326                 rc = -EINVAL;
 327                 goto out;
 328         }
 329
 330         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 331                    "Correct mutex_owned() behavior\n");
 332         goto out;
 333 out_exit:
 334         mutex_exit(&mp.mp_mtx);
 335 out:
 336         mutex_destroy(&mp.mp_mtx);
 337         taskq_destroy(tq);
 338
 339         return rc;
 340 }
 341
 342 static int
 343 splat_mutex_test4(struct file *file, void *arg)
 344 {
 345         kmutex_t mtx;
 346         kthread_t *owner;
 347         int rc = 0;
 348
 349         mutex_init(&mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 350
 351         /*
 352          * Verify mutex owner is cleared after being dropped.  Depending
 353          * on how you build your kernel this behavior changes, ensure the
 354          * SPL mutex implementation is properly detecting this.
 355          */
 356         mutex_enter(&mtx);
 357         msleep(100);
 358         mutex_exit(&mtx);
 359         if (MUTEX_HELD(&mtx)) {
 360                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 361                            "not be held, bit is by %p\n", mutex_owner(&mtx));
 362                 rc = -EINVAL;
 363                 goto out;
 364         }
 365
 366         mutex_enter(&mtx);
 367
 368         /* Mutex should be owned by current */
 369         owner = mutex_owner(&mtx);
 370         if (current != owner) {
 371                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 372                            "be owned by pid %d but is owned by pid %d\n",
 373                            current->pid, owner ? owner->pid : -1);
 374                 rc = -EINVAL;
 375                 goto out;
 376         }
 377
 378         mutex_exit(&mtx);
 379
 380         /* Mutex should not be owned by any task */
 381         owner = mutex_owner(&mtx);
 382         if (owner) {
 383                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should not "
 384                            "be owned but is owned by pid %d\n", owner->pid);
 385                 rc = -EINVAL;
 386                 goto out;
 387         }
 388
 389         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 390                    "Correct mutex_owner() behavior\n");
 391 out:
 392         mutex_destroy(&mtx);
 393
 394         return rc;
 395 }
 396
 397 splat_subsystem_t *
 398 splat_mutex_init(void)
 399 {
 400         splat_subsystem_t *sub;
 401
 402         sub = kmalloc(sizeof(*sub), GFP_KERNEL);
 403         if (sub == NULL)
 404                 return NULL;
 405
 406         memset(sub, 0, sizeof(*sub));
 407         strncpy(sub->desc.name, SPLAT_MUTEX_NAME, SPLAT_NAME_SIZE);
 408         strncpy(sub->desc.desc, SPLAT_MUTEX_DESC, SPLAT_DESC_SIZE);
 409         INIT_LIST_HEAD(&sub->subsystem_list);
 410         INIT_LIST_HEAD(&sub->test_list);
 411         spin_lock_init(&sub->test_lock);
 412         sub->desc.id = SPLAT_SUBSYSTEM_MUTEX;
 413
 414         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST1_NAME, SPLAT_MUTEX_TEST1_DESC,
 415                       SPLAT_MUTEX_TEST1_ID, splat_mutex_test1);
 416         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST2_NAME, SPLAT_MUTEX_TEST2_DESC,
 417                       SPLAT_MUTEX_TEST2_ID, splat_mutex_test2);
 418         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST3_NAME, SPLAT_MUTEX_TEST3_DESC,
 419                       SPLAT_MUTEX_TEST3_ID, splat_mutex_test3);
 420         SPLAT_TEST_INIT(sub, SPLAT_MUTEX_TEST4_NAME, SPLAT_MUTEX_TEST4_DESC,
 421                       SPLAT_MUTEX_TEST4_ID, splat_mutex_test4);
 422
 423         return sub;
 424 }
 425
 426 void
 427 splat_mutex_fini(splat_subsystem_t *sub)
 428 {
 429         ASSERT(sub);
 430         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST4_ID);
 431         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST3_ID);
 432         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST2_ID);
 433         SPLAT_TEST_FINI(sub, SPLAT_MUTEX_TEST1_ID);
 434
 435         kfree(sub);
 436 }
 437
 438 int
 439 splat_mutex_id(void) {
 440         return SPLAT_SUBSYSTEM_MUTEX;
 441 }