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         taskqid_t id;
  85         int rc = 0;
  86
  87         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
  88         if (mp == NULL)
  89                 return -ENOMEM;
  90
  91         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, 1, defclsyspri,
  92                           50, INT_MAX, TASKQ_PREPOPULATE);
  93         if (tq == NULL) {
  94                 rc = -ENOMEM;
  95                 goto out2;
  96         }
  97
  98         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
  99         mp->mp_file = file;
 100         mutex_init(&mp->mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 101         mutex_enter(&mp->mp_mtx);
 102
 103         /*
 104          * Schedule a task function which will try and acquire the mutex via
 105          * mutex_tryenter() while it's held.  This should fail and the task
 106          * function will indicate this status in the passed private data.
 107          */
 108         mp->mp_rc = -EINVAL;
 109         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 110         if (id == TASKQID_INVALID) {
 111                 mutex_exit(&mp->mp_mtx);
 112                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 113                              "taskq_dispatch() failed\n");
 114                 rc = -EINVAL;
 115                 goto out;
 116         }
 117
 118         taskq_wait_id(tq, id);
 119         mutex_exit(&mp->mp_mtx);
 120
 121         /* Task function successfully acquired mutex, very bad! */
 122         if (mp->mp_rc != -EBUSY) {
 123                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 124                     "mutex_trylock() incorrectly succeeded when "
 125                     "the mutex was held, %d/%d\n", (int)id, mp->mp_rc);
 126                 rc = -EINVAL;
 127                 goto out;
 128         } else {
 129                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 130                              "mutex_trylock() correctly failed when "
 131                              "the mutex was held\n");
 132         }
 133
 134         /*
 135          * Schedule a task function which will try and acquire the mutex via
 136          * mutex_tryenter() while it is not held.  This should succeed and
 137          * can be verified by checking the private data.
 138          */
 139         mp->mp_rc = -EINVAL;
 140         id = taskq_dispatch(tq, splat_mutex_test1_func, mp, TQ_SLEEP);
 141         if (id == TASKQID_INVALID) {
 142                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 143                              "taskq_dispatch() failed\n");
 144                 rc = -EINVAL;
 145                 goto out;
 146         }
 147
 148         taskq_wait_id(tq, id);
 149
 150         /* Task function failed to acquire mutex, very bad! */
 151         if (mp->mp_rc != 0) {
 152                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME,
 153                     "mutex_trylock() incorrectly failed when the mutex "
 154                     "was not held, %d/%d\n", (int)id, mp->mp_rc);
 155                 rc = -EINVAL;
 156         } else {
 157                 splat_vprint(file, SPLAT_MUTEX_TEST1_NAME, "%s",
 158                              "mutex_trylock() correctly succeeded "
 159                              "when the mutex was not held\n");
 160         }
 161 out:
 162         taskq_destroy(tq);
 163         mutex_destroy(&(mp->mp_mtx));
 164 out2:
 165         kfree(mp);
 166         return rc;
 167 }
 168
 169 static void
 170 splat_mutex_test2_func(void *arg)
 171 {
 172         mutex_priv_t *mp = (mutex_priv_t *)arg;
 173         int rc;
 174         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 175
 176         /* Read the value before sleeping and write it after we wake up to
 177          * maximize the chance of a race if mutexs are not working properly */
 178         mutex_enter(&mp->mp_mtx);
 179         rc = mp->mp_rc;
 180         set_current_state(TASK_INTERRUPTIBLE);
 181         schedule_timeout(HZ / 100);  /* 1/100 of a second */
 182         VERIFY(mp->mp_rc == rc);
 183         mp->mp_rc = rc + 1;
 184         mutex_exit(&mp->mp_mtx);
 185 }
 186
 187 static int
 188 splat_mutex_test2(struct file *file, void *arg)
 189 {
 190         mutex_priv_t *mp;
 191         taskq_t *tq;
 192         taskqid_t id;
 193         int i, rc = 0;
 194
 195         mp = (mutex_priv_t *)kmalloc(sizeof(*mp), GFP_KERNEL);
 196         if (mp == NULL)
 197                 return -ENOMEM;
 198
 199         /* Create several threads allowing tasks to race with each other */
 200         tq = taskq_create(SPLAT_MUTEX_TEST_TASKQ, num_online_cpus(),
 201                           defclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
 202         if (tq == NULL) {
 203                 rc = -ENOMEM;
 204                 goto out;
 205         }
 206
 207         mp->mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 208         mp->mp_file = file;
 209         mutex_init(&(mp->mp_mtx), SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 210         mp->mp_rc = 0;
 211
 212         /*
 213          * Schedule N work items to the work queue each of which enters the
 214          * mutex, sleeps briefly, then exits the mutex.  On a multiprocessor
 215          * box these work items will be handled by all available CPUs.  The
 216          * task function checks to ensure the tracked shared variable is
 217          * always only incremented by one.  Additionally, the mutex itself
 218          * is instrumented such that if any two processors are in the
 219          * critical region at the same time the system will panic.  If the
 220          * mutex is implemented right this will never happy, that's a pass.
 221          */
 222         for (i = 0; i < SPLAT_MUTEX_TEST_COUNT; i++) {
 223                 id = taskq_dispatch(tq, splat_mutex_test2_func, mp, TQ_SLEEP);
 224                 if (id == TASKQID_INVALID) {
 225                         splat_vprint(file, SPLAT_MUTEX_TEST2_NAME,
 226                                      "Failed to queue task %d\n", i);
 227                         rc = -EINVAL;
 228                 }
 229         }
 230
 231         taskq_wait(tq);
 232
 233         if (mp->mp_rc == SPLAT_MUTEX_TEST_COUNT) {
 234                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 235                            "correctly entered/exited the mutex %d times\n",
 236                            num_online_cpus(), mp->mp_rc);
 237         } else {
 238                 splat_vprint(file, SPLAT_MUTEX_TEST2_NAME, "%d racing threads "
 239                            "only processed %d/%d mutex work items\n",
 240                            num_online_cpus(),mp->mp_rc,SPLAT_MUTEX_TEST_COUNT);
 241                 rc = -EINVAL;
 242         }
 243
 244         taskq_destroy(tq);
 245         mutex_destroy(&(mp->mp_mtx));
 246 out:
 247         kfree(mp);
 248         return rc;
 249 }
 250
 251 static void
 252 splat_mutex_owned(void *priv)
 253 {
 254         mutex_priv_t *mp = (mutex_priv_t *)priv;
 255
 256         ASSERT(mp->mp_magic == SPLAT_MUTEX_TEST_MAGIC);
 257         mp->mp_rc = mutex_owned(&mp->mp_mtx);
 258         mp->mp_rc2 = MUTEX_HELD(&mp->mp_mtx);
 259 }
 260
 261 static int
 262 splat_mutex_test3(struct file *file, void *arg)
 263 {
 264         mutex_priv_t mp;
 265         taskq_t *tq;
 266         taskqid_t id;
 267         int rc = 0;
 268
 269         mp.mp_magic = SPLAT_MUTEX_TEST_MAGIC;
 270         mp.mp_file = file;
 271         mutex_init(&mp.mp_mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 272
 273         if ((tq = taskq_create(SPLAT_MUTEX_TEST_NAME, 1, defclsyspri,
 274                                50, INT_MAX, TASKQ_PREPOPULATE)) == NULL) {
 275                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Taskq '%s' "
 276                              "create failed\n", SPLAT_MUTEX_TEST3_NAME);
 277                 return -EINVAL;
 278         }
 279
 280         mutex_enter(&mp.mp_mtx);
 281
 282         /* Mutex should be owned by current */
 283         if (!mutex_owned(&mp.mp_mtx)) {
 284                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Unowned mutex "
 285                              "should be owned by pid %d\n", current->pid);
 286                 rc = -EINVAL;
 287                 goto out_exit;
 288         }
 289
 290         id = taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP);
 291         if (id == TASKQID_INVALID) {
 292                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 293                              "dispatch function '%s' to taskq\n",
 294                              sym2str(splat_mutex_owned));
 295                 rc = -EINVAL;
 296                 goto out_exit;
 297         }
 298         taskq_wait(tq);
 299
 300         /* Mutex should not be owned which checked from a different thread */
 301         if (mp.mp_rc || mp.mp_rc2) {
 302                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 303                              "pid %d not by taskq\n", current->pid);
 304                 rc = -EINVAL;
 305                 goto out_exit;
 306         }
 307
 308         mutex_exit(&mp.mp_mtx);
 309
 310         /* Mutex should not be owned by current */
 311         if (mutex_owned(&mp.mp_mtx)) {
 312                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 313                              "pid %d it should be unowned\b", current->pid);
 314                 rc = -EINVAL;
 315                 goto out;
 316         }
 317
 318         id = taskq_dispatch(tq, splat_mutex_owned, &mp, TQ_SLEEP);
 319         if (id == TASKQID_INVALID) {
 320                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Failed to "
 321                              "dispatch function '%s' to taskq\n",
 322                              sym2str(splat_mutex_owned));
 323                 rc = -EINVAL;
 324                 goto out;
 325         }
 326         taskq_wait(tq);
 327
 328         /* Mutex should be owned by no one */
 329         if (mp.mp_rc || mp.mp_rc2) {
 330                 splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "Mutex owned by "
 331                              "no one, %d/%d disagrees\n", mp.mp_rc, mp.mp_rc2);
 332                 rc = -EINVAL;
 333                 goto out;
 334         }
 335
 336         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 337                    "Correct mutex_owned() behavior\n");
 338         goto out;
 339 out_exit:
 340         mutex_exit(&mp.mp_mtx);
 341 out:
 342         mutex_destroy(&mp.mp_mtx);
 343         taskq_destroy(tq);
 344
 345         return rc;
 346 }
 347
 348 static int
 349 splat_mutex_test4(struct file *file, void *arg)
 350 {
 351         kmutex_t mtx;
 352         kthread_t *owner;
 353         int rc = 0;
 354
 355         mutex_init(&mtx, SPLAT_MUTEX_TEST_NAME, MUTEX_DEFAULT, NULL);
 356
 357         /*
 358          * Verify mutex owner is cleared after being dropped.  Depending
 359          * on how you build your kernel this behavior changes, ensure the
 360          * SPL mutex implementation is properly detecting this.
 361          */
 362         mutex_enter(&mtx);
 363         msleep(100);
 364         mutex_exit(&mtx);
 365         if (MUTEX_HELD(&mtx)) {
 366                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 367                            "not be held, bit is by %p\n", mutex_owner(&mtx));
 368                 rc = -EINVAL;
 369                 goto out;
 370         }
 371
 372         mutex_enter(&mtx);
 373
 374         /* Mutex should be owned by current */
 375         owner = mutex_owner(&mtx);
 376         if (current != owner) {
 377                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should "
 378                            "be owned by pid %d but is owned by pid %d\n",
 379                            current->pid, owner ? owner->pid : -1);
 380                 rc = -EINVAL;
 381                 goto out;
 382         }
 383
 384         mutex_exit(&mtx);
 385
 386         /* Mutex should not be owned by any task */
 387         owner = mutex_owner(&mtx);
 388         if (owner) {
 389                 splat_vprint(file, SPLAT_MUTEX_TEST4_NAME, "Mutex should not "
 390                            "be owned but is owned by pid %d\n", owner->pid);
 391                 rc = -EINVAL;
 392                 goto out;
 393         }
 394
 395         splat_vprint(file, SPLAT_MUTEX_TEST3_NAME, "%s",
 396                    "Correct mutex_owner() behavior\n");
 397 out:
 398         mutex_destroy(&mtx);
 399
 400         return rc;
 401 }
 402
 403 splat_subsystem_t *
 404 splat_mutex_init(void)
 405 {
 406         splat_subsystem_t *sub;
 407
 408         sub = kmalloc(sizeof(*sub), GFP_KERNEL);
 409         if (sub == NULL)
 410                 return NULL;
 411
 412         memset(sub, 0, sizeof(*sub));
 413         strncpy(sub->desc.name, SPLAT_MUTEX_NAME, SPLAT_NAME_SIZE);
 414         strncpy(sub->desc.desc, SPLAT_MUTEX_DESC, SPLAT_DESC_SIZE);
 415         INIT_LIST_HEAD(&sub->subsystem_list);
 416         INIT_LIST_HEAD(&sub->test_list);
 417         spin_lock_init(&sub->test_lock);
 418         sub->desc.id = SPLAT_SUBSYSTEM_MUTEX;
 419
 420         splat_test_init(sub, SPLAT_MUTEX_TEST1_NAME, SPLAT_MUTEX_TEST1_DESC,
 421                       SPLAT_MUTEX_TEST1_ID, splat_mutex_test1);
 422         splat_test_init(sub, SPLAT_MUTEX_TEST2_NAME, SPLAT_MUTEX_TEST2_DESC,
 423                       SPLAT_MUTEX_TEST2_ID, splat_mutex_test2);
 424         splat_test_init(sub, SPLAT_MUTEX_TEST3_NAME, SPLAT_MUTEX_TEST3_DESC,
 425                       SPLAT_MUTEX_TEST3_ID, splat_mutex_test3);
 426         splat_test_init(sub, SPLAT_MUTEX_TEST4_NAME, SPLAT_MUTEX_TEST4_DESC,
 427                       SPLAT_MUTEX_TEST4_ID, splat_mutex_test4);
 428
 429         return sub;
 430 }
 431
 432 void
 433 splat_mutex_fini(splat_subsystem_t *sub)
 434 {
 435         ASSERT(sub);
 436         splat_test_fini(sub, SPLAT_MUTEX_TEST4_ID);
 437         splat_test_fini(sub, SPLAT_MUTEX_TEST3_ID);
 438         splat_test_fini(sub, SPLAT_MUTEX_TEST2_ID);
 439         splat_test_fini(sub, SPLAT_MUTEX_TEST1_ID);
 440
 441         kfree(sub);
 442 }
 443
 444 int
 445 splat_mutex_id(void) {
 446         return SPLAT_SUBSYSTEM_MUTEX;
 447 }