sys/kern/kern_mutex.c

   1 /*-
   2  * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. Berkeley Software Design Inc's name may not be used to endorse or
  13  *    promote products derived from this software without specific prior
  14  *    written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  *      from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
  29  *      and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
  30  */
  31
  32 /*
  33  * Machine independent bits of mutex implementation.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #include "opt_adaptive_mutexes.h"
  40 #include "opt_ddb.h"
  41 #include "opt_global.h"
  42 #include "opt_sched.h"
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/bus.h>
  47 #include <sys/conf.h>
  48 #include <sys/kdb.h>
  49 #include <sys/kernel.h>
  50 #include <sys/ktr.h>
  51 #include <sys/lock.h>
  52 #include <sys/malloc.h>
  53 #include <sys/mutex.h>
  54 #include <sys/proc.h>
  55 #include <sys/resourcevar.h>
  56 #include <sys/sched.h>
  57 #include <sys/sbuf.h>
  58 #include <sys/sysctl.h>
  59 #include <sys/turnstile.h>
  60 #include <sys/vmmeter.h>
  61 #include <sys/lock_profile.h>
  62
  63 #include <machine/atomic.h>
  64 #include <machine/bus.h>
  65 #include <machine/cpu.h>
  66
  67 #include <ddb/ddb.h>
  68
  69 #include <fs/devfs/devfs_int.h>
  70
  71 #include <vm/vm.h>
  72 #include <vm/vm_extern.h>
  73
  74 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
  75 #define ADAPTIVE_MUTEXES
  76 #endif
  77
  78 /*
  79  * Internal utility macros.
  80  */
  81 #define mtx_unowned(m)  ((m)->mtx_lock == MTX_UNOWNED)
  82
  83 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
  84
  85 #define mtx_owner(m)    ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
  86
  87 static void     assert_mtx(struct lock_object *lock, int what);
  88 #ifdef DDB
  89 static void     db_show_mtx(struct lock_object *lock);
  90 #endif
  91 static void     lock_mtx(struct lock_object *lock, int how);
  92 static void     lock_spin(struct lock_object *lock, int how);
  93 static int      unlock_mtx(struct lock_object *lock);
  94 static int      unlock_spin(struct lock_object *lock);
  95
  96 /*
  97  * Lock classes for sleep and spin mutexes.
  98  */
  99 struct lock_class lock_class_mtx_sleep = {
 100         .lc_name = "sleep mutex",
 101         .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
 102         .lc_assert = assert_mtx,
 103 #ifdef DDB
 104         .lc_ddb_show = db_show_mtx,
 105 #endif
 106         .lc_lock = lock_mtx,
 107         .lc_unlock = unlock_mtx,
 108 };
 109 struct lock_class lock_class_mtx_spin = {
 110         .lc_name = "spin mutex",
 111         .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
 112         .lc_assert = assert_mtx,
 113 #ifdef DDB
 114         .lc_ddb_show = db_show_mtx,
 115 #endif
 116         .lc_lock = lock_spin,
 117         .lc_unlock = unlock_spin,
 118 };
 119
 120 /*
 121  * System-wide mutexes
 122  */
 123 struct mtx blocked_lock;
 124 struct mtx Giant;
 125
 126 void
 127 assert_mtx(struct lock_object *lock, int what)
 128 {
 129
 130         mtx_assert((struct mtx *)lock, what);
 131 }
 132
 133 void
 134 lock_mtx(struct lock_object *lock, int how)
 135 {
 136
 137         mtx_lock((struct mtx *)lock);
 138 }
 139
 140 void
 141 lock_spin(struct lock_object *lock, int how)
 142 {
 143
 144         panic("spin locks can only use msleep_spin");
 145 }
 146
 147 int
 148 unlock_mtx(struct lock_object *lock)
 149 {
 150         struct mtx *m;
 151
 152         m = (struct mtx *)lock;
 153         mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
 154         mtx_unlock(m);
 155         return (0);
 156 }
 157
 158 int
 159 unlock_spin(struct lock_object *lock)
 160 {
 161
 162         panic("spin locks can only use msleep_spin");
 163 }
 164
 165 /*
 166  * Function versions of the inlined __mtx_* macros.  These are used by
 167  * modules and can also be called from assembly language if needed.
 168  */
 169 void
 170 _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
 171 {
 172
 173         MPASS(curthread != NULL);
 174         KASSERT(m->mtx_lock != MTX_DESTROYED,
 175             ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
 176         KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
 177             ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
 178             file, line));
 179         WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
 180             file, line);
 181
 182         _get_sleep_lock(m, curthread, opts, file, line);
 183         LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
 184             line);
 185         WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
 186         curthread->td_locks++;
 187 }
 188
 189 void
 190 _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
 191 {
 192         MPASS(curthread != NULL);
 193         KASSERT(m->mtx_lock != MTX_DESTROYED,
 194             ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
 195         KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
 196             ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
 197             file, line));
 198         curthread->td_locks--;
 199         WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
 200         LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
 201             line);
 202         mtx_assert(m, MA_OWNED);
 203
 204         if (m->mtx_recurse == 0)
 205                 lock_profile_release_lock(&m->lock_object);
 206         _rel_sleep_lock(m, curthread, opts, file, line);
 207 }
 208
 209 void
 210 _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
 211 {
 212
 213         MPASS(curthread != NULL);
 214         KASSERT(m->mtx_lock != MTX_DESTROYED,
 215             ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
 216         KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
 217             ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
 218             m->lock_object.lo_name, file, line));
 219         if (mtx_owned(m))
 220                 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
 221             ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
 222                     m->lock_object.lo_name, file, line));
 223         WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
 224             file, line);
 225         _get_spin_lock(m, curthread, opts, file, line);
 226         LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
 227             line);
 228         WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
 229 }
 230
 231 void
 232 _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
 233 {
 234
 235         MPASS(curthread != NULL);
 236         KASSERT(m->mtx_lock != MTX_DESTROYED,
 237             ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
 238         KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
 239             ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
 240             m->lock_object.lo_name, file, line));
 241         WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
 242         LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
 243             line);
 244         mtx_assert(m, MA_OWNED);
 245
 246         _rel_spin_lock(m);
 247 }
 248
 249 /*
 250  * The important part of mtx_trylock{,_flags}()
 251  * Tries to acquire lock `m.'  If this function is called on a mutex that
 252  * is already owned, it will recursively acquire the lock.
 253  */
 254 int
 255 _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
 256 {
 257         int rval, contested = 0;
 258         uint64_t waittime = 0;
 259
 260         MPASS(curthread != NULL);
 261         KASSERT(m->mtx_lock != MTX_DESTROYED,
 262             ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
 263         KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
 264             ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
 265             file, line));
 266
 267         if (mtx_owned(m) && (m->lock_object.lo_flags & LO_RECURSABLE) != 0) {
 268                 m->mtx_recurse++;
 269                 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
 270                 rval = 1;
 271         } else
 272                 rval = _obtain_lock(m, (uintptr_t)curthread);
 273
 274         LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
 275         if (rval) {
 276                 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
 277                     file, line);
 278                 curthread->td_locks++;
 279                 if (m->mtx_recurse == 0)
 280                         lock_profile_obtain_lock_success(&m->lock_object, contested,
 281                             waittime, file, line);
 282
 283         }
 284
 285         return (rval);
 286 }
 287
 288 /*
 289  * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
 290  *
 291  * We call this if the lock is either contested (i.e. we need to go to
 292  * sleep waiting for it), or if we need to recurse on it.
 293  */
 294 void
 295 _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
 296     int line)
 297 {
 298         struct turnstile *ts;
 299 #ifdef ADAPTIVE_MUTEXES
 300         volatile struct thread *owner;
 301 #endif
 302 #ifdef KTR
 303         int cont_logged = 0;
 304 #endif
 305         int contested = 0;
 306         uint64_t waittime = 0;
 307         uintptr_t v;
 308
 309         if (mtx_owned(m)) {
 310                 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
 311             ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
 312                     m->lock_object.lo_name, file, line));
 313                 m->mtx_recurse++;
 314                 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
 315                 if (LOCK_LOG_TEST(&m->lock_object, opts))
 316                         CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
 317                 return;
 318         }
 319
 320         lock_profile_obtain_lock_failed(&m->lock_object,
 321                     &contested, &waittime);
 322         if (LOCK_LOG_TEST(&m->lock_object, opts))
 323                 CTR4(KTR_LOCK,
 324                     "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
 325                     m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
 326
 327         while (!_obtain_lock(m, tid)) {
 328 #ifdef ADAPTIVE_MUTEXES
 329                 /*
 330                  * If the owner is running on another CPU, spin until the
 331                  * owner stops running or the state of the lock changes.
 332                  */
 333                 v = m->mtx_lock;
 334                 if (v != MTX_UNOWNED) {
 335                         owner = (struct thread *)(v & ~MTX_FLAGMASK);
 336                         if (TD_IS_RUNNING(owner)) {
 337                                 if (LOCK_LOG_TEST(&m->lock_object, 0))
 338                                         CTR3(KTR_LOCK,
 339                                             "%s: spinning on %p held by %p",
 340                                             __func__, m, owner);
 341                                 while (mtx_owner(m) == owner &&
 342                                     TD_IS_RUNNING(owner))
 343                                         cpu_spinwait();
 344                                 continue;
 345                         }
 346                 }
 347 #endif
 348
 349                 ts = turnstile_trywait(&m->lock_object);
 350                 v = m->mtx_lock;
 351
 352                 /*
 353                  * Check if the lock has been released while spinning for
 354                  * the turnstile chain lock.
 355                  */
 356                 if (v == MTX_UNOWNED) {
 357                         turnstile_cancel(ts);
 358                         cpu_spinwait();
 359                         continue;
 360                 }
 361
 362                 MPASS(v != MTX_CONTESTED);
 363
 364 #ifdef ADAPTIVE_MUTEXES
 365                 /*
 366                  * If the current owner of the lock is executing on another
 367                  * CPU quit the hard path and try to spin.
 368                  */
 369                 owner = (struct thread *)(v & ~MTX_FLAGMASK);
 370                 if (TD_IS_RUNNING(owner)) {
 371                         turnstile_cancel(ts);
 372                         cpu_spinwait();
 373                         continue;
 374                 }
 375 #endif
 376
 377                 /*
 378                  * If the mutex isn't already contested and a failure occurs
 379                  * setting the contested bit, the mutex was either released
 380                  * or the state of the MTX_RECURSED bit changed.
 381                  */
 382                 if ((v & MTX_CONTESTED) == 0 &&
 383                     !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
 384                         turnstile_cancel(ts);
 385                         cpu_spinwait();
 386                         continue;
 387                 }
 388
 389                 /*
 390                  * We definitely must sleep for this lock.
 391                  */
 392                 mtx_assert(m, MA_NOTOWNED);
 393
 394 #ifdef KTR
 395                 if (!cont_logged) {
 396                         CTR6(KTR_CONTENTION,
 397                             "contention: %p at %s:%d wants %s, taken by %s:%d",
 398                             (void *)tid, file, line, m->lock_object.lo_name,
 399                             WITNESS_FILE(&m->lock_object),
 400                             WITNESS_LINE(&m->lock_object));
 401                         cont_logged = 1;
 402                 }
 403 #endif
 404
 405                 /*
 406                  * Block on the turnstile.
 407                  */
 408                 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
 409         }
 410 #ifdef KTR
 411         if (cont_logged) {
 412                 CTR4(KTR_CONTENTION,
 413                     "contention end: %s acquired by %p at %s:%d",
 414                     m->lock_object.lo_name, (void *)tid, file, line);
 415         }
 416 #endif
 417         lock_profile_obtain_lock_success(&m->lock_object, contested,
 418             waittime, file, line);
 419 }
 420
 421 static void
 422 _mtx_lock_spin_failed(struct mtx *m)
 423 {
 424         struct thread *td;
 425
 426         td = mtx_owner(m);
 427
 428         /* If the mutex is unlocked, try again. */
 429         if (td == NULL)
 430                 return;
 431
 432         printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
 433             m, m->lock_object.lo_name, td, td->td_tid);
 434 #ifdef WITNESS
 435         witness_display_spinlock(&m->lock_object, td);
 436 #endif
 437         panic("spin lock held too long");
 438 }
 439
 440 #ifdef SMP
 441 /*
 442  * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
 443  *
 444  * This is only called if we need to actually spin for the lock. Recursion
 445  * is handled inline.
 446  */
 447 void
 448 _mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file,
 449     int line)
 450 {
 451         int i = 0, contested = 0;
 452         uint64_t waittime = 0;
 453
 454         if (LOCK_LOG_TEST(&m->lock_object, opts))
 455                 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
 456
 457         lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
 458         while (!_obtain_lock(m, tid)) {
 459
 460                 /* Give interrupts a chance while we spin. */
 461                 spinlock_exit();
 462                 while (m->mtx_lock != MTX_UNOWNED) {
 463                         if (i++ < 10000000) {
 464                                 cpu_spinwait();
 465                                 continue;
 466                         }
 467                         if (i < 60000000 || kdb_active || panicstr != NULL)
 468                                 DELAY(1);
 469                         else
 470                                 _mtx_lock_spin_failed(m);
 471                         cpu_spinwait();
 472                 }
 473                 spinlock_enter();
 474         }
 475
 476         if (LOCK_LOG_TEST(&m->lock_object, opts))
 477                 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
 478
 479         lock_profile_obtain_lock_success(&m->lock_object, contested,
 480             waittime, (file), (line));
 481 }
 482 #endif /* SMP */
 483
 484 void
 485 _thread_lock_flags(struct thread *td, int opts, const char *file, int line)
 486 {
 487         struct mtx *m;
 488         uintptr_t tid;
 489         int i, contested;
 490         uint64_t waittime;
 491
 492         contested = i = 0;
 493         waittime = 0;
 494         tid = (uintptr_t)curthread;
 495         for (;;) {
 496 retry:
 497                 spinlock_enter();
 498                 m = td->td_lock;
 499                 KASSERT(m->mtx_lock != MTX_DESTROYED,
 500                     ("thread_lock() of destroyed mutex @ %s:%d", file, line));
 501                 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
 502                     ("thread_lock() of sleep mutex %s @ %s:%d",
 503                     m->lock_object.lo_name, file, line));
 504                 if (mtx_owned(m))
 505                         KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
 506             ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
 507                             m->lock_object.lo_name, file, line));
 508                 WITNESS_CHECKORDER(&m->lock_object,
 509                     opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line);
 510                 while (!_obtain_lock(m, tid)) {
 511                         if (m->mtx_lock == tid) {
 512                                 m->mtx_recurse++;
 513                                 break;
 514                         }
 515                         lock_profile_obtain_lock_failed(&m->lock_object,
 516                             &contested, &waittime);
 517                         /* Give interrupts a chance while we spin. */
 518                         spinlock_exit();
 519                         while (m->mtx_lock != MTX_UNOWNED) {
 520                                 if (i++ < 10000000)
 521                                         cpu_spinwait();
 522                                 else if (i < 60000000 ||
 523                                     kdb_active || panicstr != NULL)
 524                                         DELAY(1);
 525                                 else
 526                                         _mtx_lock_spin_failed(m);
 527                                 cpu_spinwait();
 528                                 if (m != td->td_lock)
 529                                         goto retry;
 530                         }
 531                         spinlock_enter();
 532                 }
 533                 if (m == td->td_lock)
 534                         break;
 535                 _rel_spin_lock(m);      /* does spinlock_exit() */
 536         }
 537         if (m->mtx_recurse == 0)
 538                 lock_profile_obtain_lock_success(&m->lock_object, contested,
 539                     waittime, (file), (line));
 540         LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
 541             line);
 542         WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
 543 }
 544
 545 struct mtx *
 546 thread_lock_block(struct thread *td)
 547 {
 548         struct mtx *lock;
 549
 550         spinlock_enter();
 551         THREAD_LOCK_ASSERT(td, MA_OWNED);
 552         lock = td->td_lock;
 553         td->td_lock = &blocked_lock;
 554         mtx_unlock_spin(lock);
 555
 556         return (lock);
 557 }
 558
 559 void
 560 thread_lock_unblock(struct thread *td, struct mtx *new)
 561 {
 562         mtx_assert(new, MA_OWNED);
 563         MPASS(td->td_lock == &blocked_lock);
 564         atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
 565         spinlock_exit();
 566 }
 567
 568 void
 569 thread_lock_set(struct thread *td, struct mtx *new)
 570 {
 571         struct mtx *lock;
 572
 573         mtx_assert(new, MA_OWNED);
 574         THREAD_LOCK_ASSERT(td, MA_OWNED);
 575         lock = td->td_lock;
 576         td->td_lock = new;
 577         mtx_unlock_spin(lock);
 578 }
 579
 580 /*
 581  * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
 582  *
 583  * We are only called here if the lock is recursed or contested (i.e. we
 584  * need to wake up a blocked thread).
 585  */
 586 void
 587 _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
 588 {
 589         struct turnstile *ts;
 590
 591         if (mtx_recursed(m)) {
 592                 if (--(m->mtx_recurse) == 0)
 593                         atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
 594                 if (LOCK_LOG_TEST(&m->lock_object, opts))
 595                         CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
 596                 return;
 597         }
 598
 599         /*
 600          * We have to lock the chain before the turnstile so this turnstile
 601          * can be removed from the hash list if it is empty.
 602          */
 603         turnstile_chain_lock(&m->lock_object);
 604         ts = turnstile_lookup(&m->lock_object);
 605         if (LOCK_LOG_TEST(&m->lock_object, opts))
 606                 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
 607
 608         MPASS(ts != NULL);
 609         turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
 610         _release_lock_quick(m);
 611         /*
 612          * This turnstile is now no longer associated with the mutex.  We can
 613          * unlock the chain lock so a new turnstile may take it's place.
 614          */
 615         turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
 616         turnstile_chain_unlock(&m->lock_object);
 617 }
 618
 619 /*
 620  * All the unlocking of MTX_SPIN locks is done inline.
 621  * See the _rel_spin_lock() macro for the details.
 622  */
 623
 624 /*
 625  * The backing function for the INVARIANTS-enabled mtx_assert()
 626  */
 627 #ifdef INVARIANT_SUPPORT
 628 void
 629 _mtx_assert(struct mtx *m, int what, const char *file, int line)
 630 {
 631
 632         if (panicstr != NULL || dumping)
 633                 return;
 634         switch (what) {
 635         case MA_OWNED:
 636         case MA_OWNED | MA_RECURSED:
 637         case MA_OWNED | MA_NOTRECURSED:
 638                 if (!mtx_owned(m))
 639                         panic("mutex %s not owned at %s:%d",
 640                             m->lock_object.lo_name, file, line);
 641                 if (mtx_recursed(m)) {
 642                         if ((what & MA_NOTRECURSED) != 0)
 643                                 panic("mutex %s recursed at %s:%d",
 644                                     m->lock_object.lo_name, file, line);
 645                 } else if ((what & MA_RECURSED) != 0) {
 646                         panic("mutex %s unrecursed at %s:%d",
 647                             m->lock_object.lo_name, file, line);
 648                 }
 649                 break;
 650         case MA_NOTOWNED:
 651                 if (mtx_owned(m))
 652                         panic("mutex %s owned at %s:%d",
 653                             m->lock_object.lo_name, file, line);
 654                 break;
 655         default:
 656                 panic("unknown mtx_assert at %s:%d", file, line);
 657         }
 658 }
 659 #endif
 660
 661 /*
 662  * The MUTEX_DEBUG-enabled mtx_validate()
 663  *
 664  * Most of these checks have been moved off into the LO_INITIALIZED flag
 665  * maintained by the witness code.
 666  */
 667 #ifdef MUTEX_DEBUG
 668
 669 void    mtx_validate(struct mtx *);
 670
 671 void
 672 mtx_validate(struct mtx *m)
 673 {
 674
 675 /*
 676  * XXX: When kernacc() does not require Giant we can reenable this check
 677  */
 678 #ifdef notyet
 679         /*
 680          * Can't call kernacc() from early init386(), especially when
 681          * initializing Giant mutex, because some stuff in kernacc()
 682          * requires Giant itself.
 683          */
 684         if (!cold)
 685                 if (!kernacc((caddr_t)m, sizeof(m),
 686                     VM_PROT_READ | VM_PROT_WRITE))
 687                         panic("Can't read and write to mutex %p", m);
 688 #endif
 689 }
 690 #endif
 691
 692 /*
 693  * General init routine used by the MTX_SYSINIT() macro.
 694  */
 695 void
 696 mtx_sysinit(void *arg)
 697 {
 698         struct mtx_args *margs = arg;
 699
 700         mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
 701 }
 702
 703 /*
 704  * Mutex initialization routine; initialize lock `m' of type contained in
 705  * `opts' with options contained in `opts' and name `name.'  The optional
 706  * lock type `type' is used as a general lock category name for use with
 707  * witness.
 708  */
 709 void
 710 mtx_init(struct mtx *m, const char *name, const char *type, int opts)
 711 {
 712         struct lock_class *class;
 713         int flags;
 714
 715         MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
 716                 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
 717
 718 #ifdef MUTEX_DEBUG
 719         /* Diagnostic and error correction */
 720         mtx_validate(m);
 721 #endif
 722
 723         /* Determine lock class and lock flags. */
 724         if (opts & MTX_SPIN)
 725                 class = &lock_class_mtx_spin;
 726         else
 727                 class = &lock_class_mtx_sleep;
 728         flags = 0;
 729         if (opts & MTX_QUIET)
 730                 flags |= LO_QUIET;
 731         if (opts & MTX_RECURSE)
 732                 flags |= LO_RECURSABLE;
 733         if ((opts & MTX_NOWITNESS) == 0)
 734                 flags |= LO_WITNESS;
 735         if (opts & MTX_DUPOK)
 736                 flags |= LO_DUPOK;
 737         if (opts & MTX_NOPROFILE)
 738                 flags |= LO_NOPROFILE;
 739
 740         /* Initialize mutex. */
 741         m->mtx_lock = MTX_UNOWNED;
 742         m->mtx_recurse = 0;
 743
 744         lock_init(&m->lock_object, class, name, type, flags);
 745 }
 746
 747 /*
 748  * Remove lock `m' from all_mtx queue.  We don't allow MTX_QUIET to be
 749  * passed in as a flag here because if the corresponding mtx_init() was
 750  * called with MTX_QUIET set, then it will already be set in the mutex's
 751  * flags.
 752  */
 753 void
 754 mtx_destroy(struct mtx *m)
 755 {
 756
 757         if (!mtx_owned(m))
 758                 MPASS(mtx_unowned(m));
 759         else {
 760                 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
 761
 762                 /* Perform the non-mtx related part of mtx_unlock_spin(). */
 763                 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
 764                         spinlock_exit();
 765                 else
 766                         curthread->td_locks--;
 767
 768                 /* Tell witness this isn't locked to make it happy. */
 769                 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
 770                     __LINE__);
 771         }
 772
 773         m->mtx_lock = MTX_DESTROYED;
 774         lock_destroy(&m->lock_object);
 775 }
 776
 777 /*
 778  * Intialize the mutex code and system mutexes.  This is called from the MD
 779  * startup code prior to mi_startup().  The per-CPU data space needs to be
 780  * setup before this is called.
 781  */
 782 void
 783 mutex_init(void)
 784 {
 785
 786         /* Setup turnstiles so that sleep mutexes work. */
 787         init_turnstiles();
 788
 789         /*
 790          * Initialize mutexes.
 791          */
 792         mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
 793         mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
 794         blocked_lock.mtx_lock = 0xdeadc0de;     /* Always blocked. */
 795         mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
 796         mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
 797         mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
 798         mtx_lock(&Giant);
 799 }
 800
 801 #ifdef DDB
 802 void
 803 db_show_mtx(struct lock_object *lock)
 804 {
 805         struct thread *td;
 806         struct mtx *m;
 807
 808         m = (struct mtx *)lock;
 809
 810         db_printf(" flags: {");
 811         if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
 812                 db_printf("SPIN");
 813         else
 814                 db_printf("DEF");
 815         if (m->lock_object.lo_flags & LO_RECURSABLE)
 816                 db_printf(", RECURSE");
 817         if (m->lock_object.lo_flags & LO_DUPOK)
 818                 db_printf(", DUPOK");
 819         db_printf("}\n");
 820         db_printf(" state: {");
 821         if (mtx_unowned(m))
 822                 db_printf("UNOWNED");
 823         else if (mtx_destroyed(m))
 824                 db_printf("DESTROYED");
 825         else {
 826                 db_printf("OWNED");
 827                 if (m->mtx_lock & MTX_CONTESTED)
 828                         db_printf(", CONTESTED");
 829                 if (m->mtx_lock & MTX_RECURSED)
 830                         db_printf(", RECURSED");
 831         }
 832         db_printf("}\n");
 833         if (!mtx_unowned(m) && !mtx_destroyed(m)) {
 834                 td = mtx_owner(m);
 835                 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
 836                     td->td_tid, td->td_proc->p_pid, td->td_name);
 837                 if (mtx_recursed(m))
 838                         db_printf(" recursed: %d\n", m->mtx_recurse);
 839         }
 840 }
 841 #endif