sys/kern/kern_lock.c

   1 /*-
   2  * Copyright (c) 2008 Attilio Rao <attilio@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice(s), this list of conditions and the following disclaimer as
  10  *    the first lines of this file unmodified other than the possible
  11  *    addition of one or more copyright notices.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice(s), this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  17  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19  * DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
  20  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  23  * 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 SUCH
  26  * DAMAGE.
  27  */
  28
  29 #include "opt_adaptive_lockmgrs.h"
  30 #include "opt_ddb.h"
  31 #include "opt_kdtrace.h"
  32
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD$");
  35
  36 #include <sys/param.h>
  37 #include <sys/ktr.h>
  38 #include <sys/linker_set.h>
  39 #include <sys/lock.h>
  40 #include <sys/lock_profile.h>
  41 #include <sys/lockmgr.h>
  42 #include <sys/mutex.h>
  43 #include <sys/proc.h>
  44 #include <sys/sleepqueue.h>
  45 #ifdef DEBUG_LOCKS
  46 #include <sys/stack.h>
  47 #endif
  48 #include <sys/sysctl.h>
  49 #include <sys/systm.h>
  50
  51 #include <machine/cpu.h>
  52
  53 #ifdef DDB
  54 #include <ddb/ddb.h>
  55 #endif
  56
  57 CTASSERT(((LK_ADAPTIVE | LK_NOSHARE) & LO_CLASSFLAGS) ==
  58     (LK_ADAPTIVE | LK_NOSHARE));
  59 CTASSERT(LK_UNLOCKED == (LK_UNLOCKED &
  60     ~(LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS)));
  61
  62 #define SQ_EXCLUSIVE_QUEUE      0
  63 #define SQ_SHARED_QUEUE         1
  64
  65 #ifndef INVARIANTS
  66 #define _lockmgr_assert(lk, what, file, line)
  67 #define TD_LOCKS_INC(td)
  68 #define TD_LOCKS_DEC(td)
  69 #else
  70 #define TD_LOCKS_INC(td)        ((td)->td_locks++)
  71 #define TD_LOCKS_DEC(td)        ((td)->td_locks--)
  72 #endif
  73 #define TD_SLOCKS_INC(td)       ((td)->td_lk_slocks++)
  74 #define TD_SLOCKS_DEC(td)       ((td)->td_lk_slocks--)
  75
  76 #ifndef DEBUG_LOCKS
  77 #define STACK_PRINT(lk)
  78 #define STACK_SAVE(lk)
  79 #define STACK_ZERO(lk)
  80 #else
  81 #define STACK_PRINT(lk) stack_print_ddb(&(lk)->lk_stack)
  82 #define STACK_SAVE(lk)  stack_save(&(lk)->lk_stack)
  83 #define STACK_ZERO(lk)  stack_zero(&(lk)->lk_stack)
  84 #endif
  85
  86 #define LOCK_LOG2(lk, string, arg1, arg2)                               \
  87         if (LOCK_LOG_TEST(&(lk)->lock_object, 0))                       \
  88                 CTR2(KTR_LOCK, (string), (arg1), (arg2))
  89 #define LOCK_LOG3(lk, string, arg1, arg2, arg3)                         \
  90         if (LOCK_LOG_TEST(&(lk)->lock_object, 0))                       \
  91                 CTR3(KTR_LOCK, (string), (arg1), (arg2), (arg3))
  92
  93 #define GIANT_DECLARE                                                   \
  94         int _i = 0;                                                     \
  95         WITNESS_SAVE_DECL(Giant)
  96 #define GIANT_RESTORE() do {                                            \
  97         if (_i > 0) {                                                   \
  98                 while (_i--)                                            \
  99                         mtx_lock(&Giant);                               \
 100                 WITNESS_RESTORE(&Giant.lock_object, Giant);             \
 101         }                                                               \
 102 } while (0)
 103 #define GIANT_SAVE() do {                                               \
 104         if (mtx_owned(&Giant)) {                                        \
 105                 WITNESS_SAVE(&Giant.lock_object, Giant);                \
 106                 while (mtx_owned(&Giant)) {                             \
 107                         _i++;                                           \
 108                         mtx_unlock(&Giant);                             \
 109                 }                                                       \
 110         }                                                               \
 111 } while (0)
 112
 113 #define LK_CAN_SHARE(x)                                                 \
 114         (((x) & LK_SHARE) && (((x) & LK_EXCLUSIVE_WAITERS) == 0 ||      \
 115         ((x) & LK_EXCLUSIVE_SPINNERS) == 0 ||                           \
 116         curthread->td_lk_slocks || (curthread->td_pflags & TDP_DEADLKTREAT)))
 117 #define LK_TRYOP(x)                                                     \
 118         ((x) & LK_NOWAIT)
 119
 120 #define LK_CAN_WITNESS(x)                                               \
 121         (((x) & LK_NOWITNESS) == 0 && !LK_TRYOP(x))
 122 #define LK_TRYWIT(x)                                                    \
 123         (LK_TRYOP(x) ? LOP_TRYLOCK : 0)
 124
 125 #define LK_CAN_ADAPT(lk, f)                                             \
 126         (((lk)->lock_object.lo_flags & LK_ADAPTIVE) != 0 &&             \
 127         ((f) & LK_SLEEPFAIL) == 0)
 128
 129 #define lockmgr_disowned(lk)                                            \
 130         (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == LK_KERNPROC)
 131
 132 #define lockmgr_xlocked(lk)                                             \
 133         (((lk)->lk_lock & ~(LK_FLAGMASK & ~LK_SHARE)) == (uintptr_t)curthread)
 134
 135 static void      assert_lockmgr(struct lock_object *lock, int how);
 136 #ifdef DDB
 137 static void      db_show_lockmgr(struct lock_object *lock);
 138 #endif
 139 static void      lock_lockmgr(struct lock_object *lock, int how);
 140 #ifdef KDTRACE_HOOKS
 141 static int       owner_lockmgr(struct lock_object *lock, struct thread **owner);
 142 #endif
 143 static int       unlock_lockmgr(struct lock_object *lock);
 144
 145 struct lock_class lock_class_lockmgr = {
 146         .lc_name = "lockmgr",
 147         .lc_flags = LC_RECURSABLE | LC_SLEEPABLE | LC_SLEEPLOCK | LC_UPGRADABLE,
 148         .lc_assert = assert_lockmgr,
 149 #ifdef DDB
 150         .lc_ddb_show = db_show_lockmgr,
 151 #endif
 152         .lc_lock = lock_lockmgr,
 153         .lc_unlock = unlock_lockmgr,
 154 #ifdef KDTRACE_HOOKS
 155         .lc_owner = owner_lockmgr,
 156 #endif
 157 };
 158
 159 #ifdef ADAPTIVE_LOCKMGRS
 160 static u_int alk_retries = 10;
 161 static u_int alk_loops = 10000;
 162 SYSCTL_NODE(_debug, OID_AUTO, lockmgr, CTLFLAG_RD, NULL, "lockmgr debugging");
 163 SYSCTL_UINT(_debug_lockmgr, OID_AUTO, retries, CTLFLAG_RW, &alk_retries, 0, "");
 164 SYSCTL_UINT(_debug_lockmgr, OID_AUTO, loops, CTLFLAG_RW, &alk_loops, 0, "");
 165 #endif
 166
 167 static __inline struct thread *
 168 lockmgr_xholder(struct lock *lk)
 169 {
 170         uintptr_t x;
 171
 172         x = lk->lk_lock;
 173         return ((x & LK_SHARE) ? NULL : (struct thread *)LK_HOLDER(x));
 174 }
 175
 176 /*
 177  * It assumes sleepq_lock held and returns with this one unheld.
 178  * It also assumes the generic interlock is sane and previously checked.
 179  * If LK_INTERLOCK is specified the interlock is not reacquired after the
 180  * sleep.
 181  */
 182 static __inline int
 183 sleeplk(struct lock *lk, u_int flags, struct lock_object *ilk,
 184     const char *wmesg, int pri, int timo, int queue)
 185 {
 186         GIANT_DECLARE;
 187         struct lock_class *class;
 188         int catch, error;
 189
 190         class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
 191         catch = pri & PCATCH;
 192         pri &= PRIMASK;
 193         error = 0;
 194
 195         LOCK_LOG3(lk, "%s: %p blocking on the %s sleepqueue", __func__, lk,
 196             (queue == SQ_EXCLUSIVE_QUEUE) ? "exclusive" : "shared");
 197
 198         if (flags & LK_INTERLOCK)
 199                 class->lc_unlock(ilk);
 200         GIANT_SAVE();
 201         sleepq_add(&lk->lock_object, NULL, wmesg, SLEEPQ_LK | (catch ?
 202             SLEEPQ_INTERRUPTIBLE : 0), queue);
 203         if ((flags & LK_TIMELOCK) && timo)
 204                 sleepq_set_timeout(&lk->lock_object, timo);
 205
 206         /*
 207          * Decisional switch for real sleeping.
 208          */
 209         if ((flags & LK_TIMELOCK) && timo && catch)
 210                 error = sleepq_timedwait_sig(&lk->lock_object, pri);
 211         else if ((flags & LK_TIMELOCK) && timo)
 212                 error = sleepq_timedwait(&lk->lock_object, pri);
 213         else if (catch)
 214                 error = sleepq_wait_sig(&lk->lock_object, pri);
 215         else
 216                 sleepq_wait(&lk->lock_object, pri);
 217         GIANT_RESTORE();
 218         if ((flags & LK_SLEEPFAIL) && error == 0)
 219                 error = ENOLCK;
 220
 221         return (error);
 222 }
 223
 224 static __inline int
 225 wakeupshlk(struct lock *lk, const char *file, int line)
 226 {
 227         uintptr_t v, x;
 228         int queue, wakeup_swapper;
 229
 230         TD_LOCKS_DEC(curthread);
 231         TD_SLOCKS_DEC(curthread);
 232         WITNESS_UNLOCK(&lk->lock_object, 0, file, line);
 233         LOCK_LOG_LOCK("SUNLOCK", &lk->lock_object, 0, 0, file, line);
 234
 235         wakeup_swapper = 0;
 236         for (;;) {
 237                 x = lk->lk_lock;
 238
 239                 /*
 240                  * If there is more than one shared lock held, just drop one
 241                  * and return.
 242                  */
 243                 if (LK_SHARERS(x) > 1) {
 244                         if (atomic_cmpset_ptr(&lk->lk_lock, x,
 245                             x - LK_ONE_SHARER))
 246                                 break;
 247                         continue;
 248                 }
 249
 250                 /*
 251                  * If there are not waiters on the exclusive queue, drop the
 252                  * lock quickly.
 253                  */
 254                 if ((x & LK_ALL_WAITERS) == 0) {
 255                         MPASS((x & ~LK_EXCLUSIVE_SPINNERS) ==
 256                             LK_SHARERS_LOCK(1));
 257                         if (atomic_cmpset_ptr(&lk->lk_lock, x, LK_UNLOCKED))
 258                                 break;
 259                         continue;
 260                 }
 261
 262                 /*
 263                  * We should have a sharer with waiters, so enter the hard
 264                  * path in order to handle wakeups correctly.
 265                  */
 266                 sleepq_lock(&lk->lock_object);
 267                 x = lk->lk_lock & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
 268                 v = LK_UNLOCKED;
 269
 270                 /*
 271                  * If the lock has exclusive waiters, give them preference in
 272                  * order to avoid deadlock with shared runners up.
 273                  */
 274                 if (x & LK_EXCLUSIVE_WAITERS) {
 275                         queue = SQ_EXCLUSIVE_QUEUE;
 276                         v |= (x & LK_SHARED_WAITERS);
 277                 } else {
 278                         MPASS((x & ~LK_EXCLUSIVE_SPINNERS) ==
 279                             LK_SHARED_WAITERS);
 280                         queue = SQ_SHARED_QUEUE;
 281                 }
 282
 283                 if (!atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x,
 284                     v)) {
 285                         sleepq_release(&lk->lock_object);
 286                         continue;
 287                 }
 288                 LOCK_LOG3(lk, "%s: %p waking up threads on the %s queue",
 289                     __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
 290                     "exclusive");
 291                 wakeup_swapper = sleepq_broadcast(&lk->lock_object, SLEEPQ_LK,
 292                     0, queue);
 293                 sleepq_release(&lk->lock_object);
 294                 break;
 295         }
 296
 297         lock_profile_release_lock(&lk->lock_object);
 298         return (wakeup_swapper);
 299 }
 300
 301 static void
 302 assert_lockmgr(struct lock_object *lock, int what)
 303 {
 304
 305         panic("lockmgr locks do not support assertions");
 306 }
 307
 308 static void
 309 lock_lockmgr(struct lock_object *lock, int how)
 310 {
 311
 312         panic("lockmgr locks do not support sleep interlocking");
 313 }
 314
 315 static int
 316 unlock_lockmgr(struct lock_object *lock)
 317 {
 318
 319         panic("lockmgr locks do not support sleep interlocking");
 320 }
 321
 322 #ifdef KDTRACE_HOOKS
 323 static int
 324 owner_lockmgr(struct lock_object *lock, struct thread **owner)
 325 {
 326
 327         panic("lockmgr locks do not support owner inquiring");
 328 }
 329 #endif
 330
 331 void
 332 lockinit(struct lock *lk, int pri, const char *wmesg, int timo, int flags)
 333 {
 334         int iflags;
 335
 336         MPASS((flags & ~LK_INIT_MASK) == 0);
 337
 338         iflags = LO_SLEEPABLE | LO_UPGRADABLE;
 339         if (flags & LK_CANRECURSE)
 340                 iflags |= LO_RECURSABLE;
 341         if ((flags & LK_NODUP) == 0)
 342                 iflags |= LO_DUPOK;
 343         if (flags & LK_NOPROFILE)
 344                 iflags |= LO_NOPROFILE;
 345         if ((flags & LK_NOWITNESS) == 0)
 346                 iflags |= LO_WITNESS;
 347         if (flags & LK_QUIET)
 348                 iflags |= LO_QUIET;
 349         iflags |= flags & (LK_ADAPTIVE | LK_NOSHARE);
 350
 351         lk->lk_lock = LK_UNLOCKED;
 352         lk->lk_recurse = 0;
 353         lk->lk_timo = timo;
 354         lk->lk_pri = pri;
 355         lock_init(&lk->lock_object, &lock_class_lockmgr, wmesg, NULL, iflags);
 356         STACK_ZERO(lk);
 357 }
 358
 359 void
 360 lockdestroy(struct lock *lk)
 361 {
 362
 363         KASSERT(lk->lk_lock == LK_UNLOCKED, ("lockmgr still held"));
 364         KASSERT(lk->lk_recurse == 0, ("lockmgr still recursed"));
 365         lock_destroy(&lk->lock_object);
 366 }
 367
 368 int
 369 __lockmgr_args(struct lock *lk, u_int flags, struct lock_object *ilk,
 370     const char *wmesg, int pri, int timo, const char *file, int line)
 371 {
 372         GIANT_DECLARE;
 373         struct lock_class *class;
 374         const char *iwmesg;
 375         uintptr_t tid, v, x;
 376         u_int op;
 377         int error, ipri, itimo, queue, wakeup_swapper;
 378 #ifdef LOCK_PROFILING
 379         uint64_t waittime = 0;
 380         int contested = 0;
 381 #endif
 382 #ifdef ADAPTIVE_LOCKMGRS
 383         volatile struct thread *owner;
 384         u_int i, spintries = 0;
 385 #endif
 386
 387         error = 0;
 388         tid = (uintptr_t)curthread;
 389         op = (flags & LK_TYPE_MASK);
 390         iwmesg = (wmesg == LK_WMESG_DEFAULT) ? lk->lock_object.lo_name : wmesg;
 391         ipri = (pri == LK_PRIO_DEFAULT) ? lk->lk_pri : pri;
 392         itimo = (timo == LK_TIMO_DEFAULT) ? lk->lk_timo : timo;
 393
 394         MPASS((flags & ~LK_TOTAL_MASK) == 0);
 395         KASSERT((op & (op - 1)) == 0,
 396             ("%s: Invalid requested operation @ %s:%d", __func__, file, line));
 397         KASSERT((flags & (LK_NOWAIT | LK_SLEEPFAIL)) == 0 ||
 398             (op != LK_DOWNGRADE && op != LK_RELEASE),
 399             ("%s: Invalid flags in regard of the operation desired @ %s:%d",
 400             __func__, file, line));
 401         KASSERT((flags & LK_INTERLOCK) == 0 || ilk != NULL,
 402             ("%s: LK_INTERLOCK passed without valid interlock @ %s:%d",
 403             __func__, file, line));
 404
 405         class = (flags & LK_INTERLOCK) ? LOCK_CLASS(ilk) : NULL;
 406         if (panicstr != NULL) {
 407                 if (flags & LK_INTERLOCK)
 408                         class->lc_unlock(ilk);
 409                 return (0);
 410         }
 411
 412         if (op == LK_SHARED && (lk->lock_object.lo_flags & LK_NOSHARE))
 413                 op = LK_EXCLUSIVE;
 414
 415         wakeup_swapper = 0;
 416         switch (op) {
 417         case LK_SHARED:
 418                 if (LK_CAN_WITNESS(flags))
 419                         WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER,
 420                             file, line, ilk);
 421                 for (;;) {
 422                         x = lk->lk_lock;
 423
 424                         /*
 425                          * If no other thread has an exclusive lock, or
 426                          * no exclusive waiter is present, bump the count of
 427                          * sharers.  Since we have to preserve the state of
 428                          * waiters, if we fail to acquire the shared lock
 429                          * loop back and retry.
 430                          */
 431                         if (LK_CAN_SHARE(x)) {
 432                                 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
 433                                     x + LK_ONE_SHARER))
 434                                         break;
 435                                 continue;
 436                         }
 437                         lock_profile_obtain_lock_failed(&lk->lock_object,
 438                             &contested, &waittime);
 439
 440                         /*
 441                          * If the lock is already held by curthread in
 442                          * exclusive way avoid a deadlock.
 443                          */
 444                         if (LK_HOLDER(x) == tid) {
 445                                 LOCK_LOG2(lk,
 446                                     "%s: %p already held in exclusive mode",
 447                                     __func__, lk);
 448                                 error = EDEADLK;
 449                                 break;
 450                         }
 451
 452                         /*
 453                          * If the lock is expected to not sleep just give up
 454                          * and return.
 455                          */
 456                         if (LK_TRYOP(flags)) {
 457                                 LOCK_LOG2(lk, "%s: %p fails the try operation",
 458                                     __func__, lk);
 459                                 error = EBUSY;
 460                                 break;
 461                         }
 462
 463 #ifdef ADAPTIVE_LOCKMGRS
 464                         /*
 465                          * If the owner is running on another CPU, spin until
 466                          * the owner stops running or the state of the lock
 467                          * changes.
 468                          */
 469                         if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
 470                             LK_HOLDER(x) != LK_KERNPROC) {
 471                                 owner = (struct thread *)LK_HOLDER(x);
 472                                 if (LOCK_LOG_TEST(&lk->lock_object, 0))
 473                                         CTR3(KTR_LOCK,
 474                                             "%s: spinning on %p held by %p",
 475                                             __func__, lk, owner);
 476
 477                                 /*
 478                                  * If we are holding also an interlock drop it
 479                                  * in order to avoid a deadlock if the lockmgr
 480                                  * owner is adaptively spinning on the
 481                                  * interlock itself.
 482                                  */
 483                                 if (flags & LK_INTERLOCK) {
 484                                         class->lc_unlock(ilk);
 485                                         flags &= ~LK_INTERLOCK;
 486                                 }
 487                                 GIANT_SAVE();
 488                                 while (LK_HOLDER(lk->lk_lock) ==
 489                                     (uintptr_t)owner && TD_IS_RUNNING(owner))
 490                                         cpu_spinwait();
 491                         } else if (LK_CAN_ADAPT(lk, flags) &&
 492                             (x & LK_SHARE) !=0 && LK_SHARERS(x) &&
 493                             spintries < alk_retries) {
 494                                 if (flags & LK_INTERLOCK) {
 495                                         class->lc_unlock(ilk);
 496                                         flags &= ~LK_INTERLOCK;
 497                                 }
 498                                 GIANT_SAVE();
 499                                 spintries++;
 500                                 for (i = 0; i < alk_loops; i++) {
 501                                         if (LOCK_LOG_TEST(&lk->lock_object, 0))
 502                                                 CTR4(KTR_LOCK,
 503                                     "%s: shared spinning on %p with %u and %u",
 504                                                     __func__, lk, spintries, i);
 505                                         x = lk->lk_lock;
 506                                         if ((x & LK_SHARE) == 0 ||
 507                                             LK_CAN_SHARE(x) != 0)
 508                                                 break;
 509                                         cpu_spinwait();
 510                                 }
 511                                 if (i != alk_loops)
 512                                         continue;
 513                         }
 514 #endif
 515
 516                         /*
 517                          * Acquire the sleepqueue chain lock because we
 518                          * probabilly will need to manipulate waiters flags.
 519                          */
 520                         sleepq_lock(&lk->lock_object);
 521                         x = lk->lk_lock;
 522
 523                         /*
 524                          * if the lock can be acquired in shared mode, try
 525                          * again.
 526                          */
 527                         if (LK_CAN_SHARE(x)) {
 528                                 sleepq_release(&lk->lock_object);
 529                                 continue;
 530                         }
 531
 532 #ifdef ADAPTIVE_LOCKMGRS
 533                         /*
 534                          * The current lock owner might have started executing
 535                          * on another CPU (or the lock could have changed
 536                          * owner) while we were waiting on the turnstile
 537                          * chain lock.  If so, drop the turnstile lock and try
 538                          * again.
 539                          */
 540                         if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
 541                             LK_HOLDER(x) != LK_KERNPROC) {
 542                                 owner = (struct thread *)LK_HOLDER(x);
 543                                 if (TD_IS_RUNNING(owner)) {
 544                                         sleepq_release(&lk->lock_object);
 545                                         continue;
 546                                 }
 547                         }
 548 #endif
 549
 550                         /*
 551                          * Try to set the LK_SHARED_WAITERS flag.  If we fail,
 552                          * loop back and retry.
 553                          */
 554                         if ((x & LK_SHARED_WAITERS) == 0) {
 555                                 if (!atomic_cmpset_acq_ptr(&lk->lk_lock, x,
 556                                     x | LK_SHARED_WAITERS)) {
 557                                         sleepq_release(&lk->lock_object);
 558                                         continue;
 559                                 }
 560                                 LOCK_LOG2(lk, "%s: %p set shared waiters flag",
 561                                     __func__, lk);
 562                         }
 563
 564                         /*
 565                          * As far as we have been unable to acquire the
 566                          * shared lock and the shared waiters flag is set,
 567                          * we will sleep.
 568                          */
 569                         error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
 570                             SQ_SHARED_QUEUE);
 571                         flags &= ~LK_INTERLOCK;
 572                         if (error) {
 573                                 LOCK_LOG3(lk,
 574                                     "%s: interrupted sleep for %p with %d",
 575                                     __func__, lk, error);
 576                                 break;
 577                         }
 578                         LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
 579                             __func__, lk);
 580                 }
 581                 if (error == 0) {
 582                         lock_profile_obtain_lock_success(&lk->lock_object,
 583                             contested, waittime, file, line);
 584                         LOCK_LOG_LOCK("SLOCK", &lk->lock_object, 0, 0, file,
 585                             line);
 586                         WITNESS_LOCK(&lk->lock_object, LK_TRYWIT(flags), file,
 587                             line);
 588                         TD_LOCKS_INC(curthread);
 589                         TD_SLOCKS_INC(curthread);
 590                         STACK_SAVE(lk);
 591                 }
 592                 break;
 593         case LK_UPGRADE:
 594                 _lockmgr_assert(lk, KA_SLOCKED, file, line);
 595                 v = lk->lk_lock;
 596                 x = v & LK_ALL_WAITERS;
 597                 v &= LK_EXCLUSIVE_SPINNERS;
 598
 599                 /*
 600                  * Try to switch from one shared lock to an exclusive one.
 601                  * We need to preserve waiters flags during the operation.
 602                  */
 603                 if (atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x | v,
 604                     tid | x)) {
 605                         LOCK_LOG_LOCK("XUPGRADE", &lk->lock_object, 0, 0, file,
 606                             line);
 607                         WITNESS_UPGRADE(&lk->lock_object, LOP_EXCLUSIVE |
 608                             LK_TRYWIT(flags), file, line);
 609                         TD_SLOCKS_DEC(curthread);
 610                         break;
 611                 }
 612
 613                 /*
 614                  * We have been unable to succeed in upgrading, so just
 615                  * give up the shared lock.
 616                  */
 617                 wakeup_swapper |= wakeupshlk(lk, file, line);
 618
 619                 /* FALLTHROUGH */
 620         case LK_EXCLUSIVE:
 621                 if (LK_CAN_WITNESS(flags))
 622                         WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
 623                             LOP_EXCLUSIVE, file, line, ilk);
 624
 625                 /*
 626                  * If curthread already holds the lock and this one is
 627                  * allowed to recurse, simply recurse on it.
 628                  */
 629                 if (lockmgr_xlocked(lk)) {
 630                         if ((flags & LK_CANRECURSE) == 0 &&
 631                             (lk->lock_object.lo_flags & LO_RECURSABLE) == 0) {
 632
 633                                 /*
 634                                  * If the lock is expected to not panic just
 635                                  * give up and return.
 636                                  */
 637                                 if (LK_TRYOP(flags)) {
 638                                         LOCK_LOG2(lk,
 639                                             "%s: %p fails the try operation",
 640                                             __func__, lk);
 641                                         error = EBUSY;
 642                                         break;
 643                                 }
 644                                 if (flags & LK_INTERLOCK)
 645                                         class->lc_unlock(ilk);
 646                 panic("%s: recursing on non recursive lockmgr %s @ %s:%d\n",
 647                                     __func__, iwmesg, file, line);
 648                         }
 649                         lk->lk_recurse++;
 650                         LOCK_LOG2(lk, "%s: %p recursing", __func__, lk);
 651                         LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
 652                             lk->lk_recurse, file, line);
 653                         WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
 654                             LK_TRYWIT(flags), file, line);
 655                         TD_LOCKS_INC(curthread);
 656                         break;
 657                 }
 658
 659                 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED,
 660                     tid)) {
 661                         lock_profile_obtain_lock_failed(&lk->lock_object,
 662                             &contested, &waittime);
 663
 664                         /*
 665                          * If the lock is expected to not sleep just give up
 666                          * and return.
 667                          */
 668                         if (LK_TRYOP(flags)) {
 669                                 LOCK_LOG2(lk, "%s: %p fails the try operation",
 670                                     __func__, lk);
 671                                 error = EBUSY;
 672                                 break;
 673                         }
 674
 675 #ifdef ADAPTIVE_LOCKMGRS
 676                         /*
 677                          * If the owner is running on another CPU, spin until
 678                          * the owner stops running or the state of the lock
 679                          * changes.
 680                          */
 681                         x = lk->lk_lock;
 682                         if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
 683                             LK_HOLDER(x) != LK_KERNPROC) {
 684                                 owner = (struct thread *)LK_HOLDER(x);
 685                                 if (LOCK_LOG_TEST(&lk->lock_object, 0))
 686                                         CTR3(KTR_LOCK,
 687                                             "%s: spinning on %p held by %p",
 688                                             __func__, lk, owner);
 689
 690                                 /*
 691                                  * If we are holding also an interlock drop it
 692                                  * in order to avoid a deadlock if the lockmgr
 693                                  * owner is adaptively spinning on the
 694                                  * interlock itself.
 695                                  */
 696                                 if (flags & LK_INTERLOCK) {
 697                                         class->lc_unlock(ilk);
 698                                         flags &= ~LK_INTERLOCK;
 699                                 }
 700                                 GIANT_SAVE();
 701                                 while (LK_HOLDER(lk->lk_lock) ==
 702                                     (uintptr_t)owner && TD_IS_RUNNING(owner))
 703                                         cpu_spinwait();
 704                         } else if (LK_CAN_ADAPT(lk, flags) &&
 705                             (x & LK_SHARE) != 0 && LK_SHARERS(x) &&
 706                             spintries < alk_retries) {
 707                                 if ((x & LK_EXCLUSIVE_SPINNERS) == 0 &&
 708                                     !atomic_cmpset_ptr(&lk->lk_lock, x,
 709                                     x | LK_EXCLUSIVE_SPINNERS))
 710                                         continue;
 711                                 if (flags & LK_INTERLOCK) {
 712                                         class->lc_unlock(ilk);
 713                                         flags &= ~LK_INTERLOCK;
 714                                 }
 715                                 GIANT_SAVE();
 716                                 spintries++;
 717                                 for (i = 0; i < alk_loops; i++) {
 718                                         if (LOCK_LOG_TEST(&lk->lock_object, 0))
 719                                                 CTR4(KTR_LOCK,
 720                                     "%s: shared spinning on %p with %u and %u",
 721                                                     __func__, lk, spintries, i);
 722                                         if ((lk->lk_lock &
 723                                             LK_EXCLUSIVE_SPINNERS) == 0)
 724                                                 break;
 725                                         cpu_spinwait();
 726                                 }
 727                                 if (i != alk_loops)
 728                                         continue;
 729                         }
 730 #endif
 731
 732                         /*
 733                          * Acquire the sleepqueue chain lock because we
 734                          * probabilly will need to manipulate waiters flags.
 735                          */
 736                         sleepq_lock(&lk->lock_object);
 737                         x = lk->lk_lock;
 738
 739                         /*
 740                          * if the lock has been released while we spun on
 741                          * the sleepqueue chain lock just try again.
 742                          */
 743                         if (x == LK_UNLOCKED) {
 744                                 sleepq_release(&lk->lock_object);
 745                                 continue;
 746                         }
 747
 748 #ifdef ADAPTIVE_LOCKMGRS
 749                         /*
 750                          * The current lock owner might have started executing
 751                          * on another CPU (or the lock could have changed
 752                          * owner) while we were waiting on the turnstile
 753                          * chain lock.  If so, drop the turnstile lock and try
 754                          * again.
 755                          */
 756                         if (LK_CAN_ADAPT(lk, flags) && (x & LK_SHARE) == 0 &&
 757                             LK_HOLDER(x) != LK_KERNPROC) {
 758                                 owner = (struct thread *)LK_HOLDER(x);
 759                                 if (TD_IS_RUNNING(owner)) {
 760                                         sleepq_release(&lk->lock_object);
 761                                         continue;
 762                                 }
 763                         }
 764 #endif
 765
 766                         /*
 767                          * The lock can be in the state where there is a
 768                          * pending queue of waiters, but still no owner.
 769                          * This happens when the lock is contested and an
 770                          * owner is going to claim the lock.
 771                          * If curthread is the one successfully acquiring it
 772                          * claim lock ownership and return, preserving waiters
 773                          * flags.
 774                          */
 775                         v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
 776                         if ((x & ~v) == LK_UNLOCKED) {
 777                                 v &= ~LK_EXCLUSIVE_SPINNERS;
 778                                 if (atomic_cmpset_acq_ptr(&lk->lk_lock, x,
 779                                     tid | v)) {
 780                                         sleepq_release(&lk->lock_object);
 781                                         LOCK_LOG2(lk,
 782                                             "%s: %p claimed by a new writer",
 783                                             __func__, lk);
 784                                         break;
 785                                 }
 786                                 sleepq_release(&lk->lock_object);
 787                                 continue;
 788                         }
 789
 790                         /*
 791                          * Try to set the LK_EXCLUSIVE_WAITERS flag.  If we
 792                          * fail, loop back and retry.
 793                          */
 794                         if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
 795                                 if (!atomic_cmpset_ptr(&lk->lk_lock, x,
 796                                     x | LK_EXCLUSIVE_WAITERS)) {
 797                                         sleepq_release(&lk->lock_object);
 798                                         continue;
 799                                 }
 800                                 LOCK_LOG2(lk, "%s: %p set excl waiters flag",
 801                                     __func__, lk);
 802                         }
 803
 804                         /*
 805                          * As far as we have been unable to acquire the
 806                          * exclusive lock and the exclusive waiters flag
 807                          * is set, we will sleep.
 808                          */
 809                         error = sleeplk(lk, flags, ilk, iwmesg, ipri, itimo,
 810                             SQ_EXCLUSIVE_QUEUE);
 811                         flags &= ~LK_INTERLOCK;
 812                         if (error) {
 813                                 LOCK_LOG3(lk,
 814                                     "%s: interrupted sleep for %p with %d",
 815                                     __func__, lk, error);
 816                                 break;
 817                         }
 818                         LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
 819                             __func__, lk);
 820                 }
 821                 if (error == 0) {
 822                         lock_profile_obtain_lock_success(&lk->lock_object,
 823                             contested, waittime, file, line);
 824                         LOCK_LOG_LOCK("XLOCK", &lk->lock_object, 0,
 825                             lk->lk_recurse, file, line);
 826                         WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
 827                             LK_TRYWIT(flags), file, line);
 828                         TD_LOCKS_INC(curthread);
 829                         STACK_SAVE(lk);
 830                 }
 831                 break;
 832         case LK_DOWNGRADE:
 833                 _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
 834                 LOCK_LOG_LOCK("XDOWNGRADE", &lk->lock_object, 0, 0, file, line);
 835                 WITNESS_DOWNGRADE(&lk->lock_object, 0, file, line);
 836                 TD_SLOCKS_INC(curthread);
 837
 838                 /*
 839                  * In order to preserve waiters flags, just spin.
 840                  */
 841                 for (;;) {
 842                         x = lk->lk_lock;
 843                         MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
 844                         x &= LK_ALL_WAITERS;
 845                         if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
 846                             LK_SHARERS_LOCK(1) | x))
 847                                 break;
 848                         cpu_spinwait();
 849                 }
 850                 break;
 851         case LK_RELEASE:
 852                 _lockmgr_assert(lk, KA_LOCKED, file, line);
 853                 x = lk->lk_lock;
 854
 855                 if ((x & LK_SHARE) == 0) {
 856
 857                         /*
 858                          * As first option, treact the lock as if it has not
 859                          * any waiter.
 860                          * Fix-up the tid var if the lock has been disowned.
 861                          */
 862                         if (LK_HOLDER(x) == LK_KERNPROC)
 863                                 tid = LK_KERNPROC;
 864                         else {
 865                                 WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE,
 866                                     file, line);
 867                                 TD_LOCKS_DEC(curthread);
 868                         }
 869                         LOCK_LOG_LOCK("XUNLOCK", &lk->lock_object, 0,
 870                             lk->lk_recurse, file, line);
 871
 872                         /*
 873                          * The lock is held in exclusive mode.
 874                          * If the lock is recursed also, then unrecurse it.
 875                          */
 876                         if (lockmgr_xlocked(lk) && lockmgr_recursed(lk)) {
 877                                 LOCK_LOG2(lk, "%s: %p unrecursing", __func__,
 878                                     lk);
 879                                 lk->lk_recurse--;
 880                                 break;
 881                         }
 882                         if (tid != LK_KERNPROC)
 883                                 lock_profile_release_lock(&lk->lock_object);
 884
 885                         if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid,
 886                             LK_UNLOCKED))
 887                                 break;
 888
 889                         sleepq_lock(&lk->lock_object);
 890                         x = lk->lk_lock;
 891                         v = LK_UNLOCKED;
 892
 893                         /*
 894                          * If the lock has exclusive waiters, give them
 895                          * preference in order to avoid deadlock with
 896                          * shared runners up.
 897                          */
 898                         MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
 899                         if (x & LK_EXCLUSIVE_WAITERS) {
 900                                 queue = SQ_EXCLUSIVE_QUEUE;
 901                                 v |= (x & LK_SHARED_WAITERS);
 902                         } else {
 903                                 MPASS((x & LK_ALL_WAITERS) ==
 904                                     LK_SHARED_WAITERS);
 905                                 queue = SQ_SHARED_QUEUE;
 906                         }
 907
 908                         LOCK_LOG3(lk,
 909                             "%s: %p waking up threads on the %s queue",
 910                             __func__, lk, queue == SQ_SHARED_QUEUE ? "shared" :
 911                             "exclusive");
 912                         atomic_store_rel_ptr(&lk->lk_lock, v);
 913                         wakeup_swapper = sleepq_broadcast(&lk->lock_object,
 914                             SLEEPQ_LK, 0, queue);
 915                         sleepq_release(&lk->lock_object);
 916                         break;
 917                 } else
 918                         wakeup_swapper = wakeupshlk(lk, file, line);
 919                 break;
 920         case LK_DRAIN:
 921                 if (LK_CAN_WITNESS(flags))
 922                         WITNESS_CHECKORDER(&lk->lock_object, LOP_NEWORDER |
 923                             LOP_EXCLUSIVE, file, line, ilk);
 924
 925                 /*
 926                  * Trying to drain a lock we already own will result in a
 927                  * deadlock.
 928                  */
 929                 if (lockmgr_xlocked(lk)) {
 930                         if (flags & LK_INTERLOCK)
 931                                 class->lc_unlock(ilk);
 932                         panic("%s: draining %s with the lock held @ %s:%d\n",
 933                             __func__, iwmesg, file, line);
 934                 }
 935
 936                 while (!atomic_cmpset_acq_ptr(&lk->lk_lock, LK_UNLOCKED, tid)) {
 937                         lock_profile_obtain_lock_failed(&lk->lock_object,
 938                             &contested, &waittime);
 939
 940                         /*
 941                          * If the lock is expected to not sleep just give up
 942                          * and return.
 943                          */
 944                         if (LK_TRYOP(flags)) {
 945                                 LOCK_LOG2(lk, "%s: %p fails the try operation",
 946                                     __func__, lk);
 947                                 error = EBUSY;
 948                                 break;
 949                         }
 950
 951                         /*
 952                          * Acquire the sleepqueue chain lock because we
 953                          * probabilly will need to manipulate waiters flags.
 954                          */
 955                         sleepq_lock(&lk->lock_object);
 956                         x = lk->lk_lock;
 957
 958                         /*
 959                          * if the lock has been released while we spun on
 960                          * the sleepqueue chain lock just try again.
 961                          */
 962                         if (x == LK_UNLOCKED) {
 963                                 sleepq_release(&lk->lock_object);
 964                                 continue;
 965                         }
 966
 967                         v = x & (LK_ALL_WAITERS | LK_EXCLUSIVE_SPINNERS);
 968                         if ((x & ~v) == LK_UNLOCKED) {
 969                                 v = (x & ~LK_EXCLUSIVE_SPINNERS);
 970                                 if (v & LK_EXCLUSIVE_WAITERS) {
 971                                         queue = SQ_EXCLUSIVE_QUEUE;
 972                                         v &= ~LK_EXCLUSIVE_WAITERS;
 973                                 } else {
 974                                         MPASS(v & LK_SHARED_WAITERS);
 975                                         queue = SQ_SHARED_QUEUE;
 976                                         v &= ~LK_SHARED_WAITERS;
 977                                 }
 978                                 if (!atomic_cmpset_ptr(&lk->lk_lock, x, v)) {
 979                                         sleepq_release(&lk->lock_object);
 980                                         continue;
 981                                 }
 982                                 LOCK_LOG3(lk,
 983                                 "%s: %p waking up all threads on the %s queue",
 984                                     __func__, lk, queue == SQ_SHARED_QUEUE ?
 985                                     "shared" : "exclusive");
 986                                 wakeup_swapper |= sleepq_broadcast(
 987                                     &lk->lock_object, SLEEPQ_LK, 0, queue);
 988
 989                                 /*
 990                                  * If shared waiters have been woken up we need
 991                                  * to wait for one of them to acquire the lock
 992                                  * before to set the exclusive waiters in
 993                                  * order to avoid a deadlock.
 994                                  */
 995                                 if (queue == SQ_SHARED_QUEUE) {
 996                                         for (v = lk->lk_lock;
 997                                             (v & LK_SHARE) && !LK_SHARERS(v);
 998                                             v = lk->lk_lock)
 999                                                 cpu_spinwait();
1000                                 }
1001                         }
1002
1003                         /*
1004                          * Try to set the LK_EXCLUSIVE_WAITERS flag.  If we
1005                          * fail, loop back and retry.
1006                          */
1007                         if ((x & LK_EXCLUSIVE_WAITERS) == 0) {
1008                                 if (!atomic_cmpset_ptr(&lk->lk_lock, x,
1009                                     x | LK_EXCLUSIVE_WAITERS)) {
1010                                         sleepq_release(&lk->lock_object);
1011                                         continue;
1012                                 }
1013                                 LOCK_LOG2(lk, "%s: %p set drain waiters flag",
1014                                     __func__, lk);
1015                         }
1016
1017                         /*
1018                          * As far as we have been unable to acquire the
1019                          * exclusive lock and the exclusive waiters flag
1020                          * is set, we will sleep.
1021                          */
1022                         if (flags & LK_INTERLOCK) {
1023                                 class->lc_unlock(ilk);
1024                                 flags &= ~LK_INTERLOCK;
1025                         }
1026                         GIANT_SAVE();
1027                         sleepq_add(&lk->lock_object, NULL, iwmesg, SLEEPQ_LK,
1028                             SQ_EXCLUSIVE_QUEUE);
1029                         sleepq_wait(&lk->lock_object, ipri & PRIMASK);
1030                         GIANT_RESTORE();
1031                         LOCK_LOG2(lk, "%s: %p resuming from the sleep queue",
1032                             __func__, lk);
1033                 }
1034
1035                 if (error == 0) {
1036                         lock_profile_obtain_lock_success(&lk->lock_object,
1037                             contested, waittime, file, line);
1038                         LOCK_LOG_LOCK("DRAIN", &lk->lock_object, 0,
1039                             lk->lk_recurse, file, line);
1040                         WITNESS_LOCK(&lk->lock_object, LOP_EXCLUSIVE |
1041                             LK_TRYWIT(flags), file, line);
1042                         TD_LOCKS_INC(curthread);
1043                         STACK_SAVE(lk);
1044                 }
1045                 break;
1046         default:
1047                 if (flags & LK_INTERLOCK)
1048                         class->lc_unlock(ilk);
1049                 panic("%s: unknown lockmgr request 0x%x\n", __func__, op);
1050         }
1051
1052         if (flags & LK_INTERLOCK)
1053                 class->lc_unlock(ilk);
1054         if (wakeup_swapper)
1055                 kick_proc0();
1056
1057         return (error);
1058 }
1059
1060 void
1061 _lockmgr_disown(struct lock *lk, const char *file, int line)
1062 {
1063         uintptr_t tid, x;
1064
1065         tid = (uintptr_t)curthread;
1066         _lockmgr_assert(lk, KA_XLOCKED | KA_NOTRECURSED, file, line);
1067
1068         /*
1069          * If the owner is already LK_KERNPROC just skip the whole operation.
1070          */
1071         if (LK_HOLDER(lk->lk_lock) != tid)
1072                 return;
1073         lock_profile_release_lock(&lk->lock_object);
1074         LOCK_LOG_LOCK("XDISOWN", &lk->lock_object, 0, 0, file, line);
1075         WITNESS_UNLOCK(&lk->lock_object, LOP_EXCLUSIVE, file, line);
1076         TD_LOCKS_DEC(curthread);
1077
1078         /*
1079          * In order to preserve waiters flags, just spin.
1080          */
1081         for (;;) {
1082                 x = lk->lk_lock;
1083                 MPASS((x & LK_EXCLUSIVE_SPINNERS) == 0);
1084                 x &= LK_ALL_WAITERS;
1085                 if (atomic_cmpset_rel_ptr(&lk->lk_lock, tid | x,
1086                     LK_KERNPROC | x))
1087                         return;
1088                 cpu_spinwait();
1089         }
1090 }
1091
1092 void
1093 lockmgr_printinfo(struct lock *lk)
1094 {
1095         struct thread *td;
1096         uintptr_t x;
1097
1098         if (lk->lk_lock == LK_UNLOCKED)
1099                 printf("lock type %s: UNLOCKED\n", lk->lock_object.lo_name);
1100         else if (lk->lk_lock & LK_SHARE)
1101                 printf("lock type %s: SHARED (count %ju)\n",
1102                     lk->lock_object.lo_name,
1103                     (uintmax_t)LK_SHARERS(lk->lk_lock));
1104         else {
1105                 td = lockmgr_xholder(lk);
1106                 printf("lock type %s: EXCL by thread %p (pid %d)\n",
1107                     lk->lock_object.lo_name, td, td->td_proc->p_pid);
1108         }
1109
1110         x = lk->lk_lock;
1111         if (x & LK_EXCLUSIVE_WAITERS)
1112                 printf(" with exclusive waiters pending\n");
1113         if (x & LK_SHARED_WAITERS)
1114                 printf(" with shared waiters pending\n");
1115         if (x & LK_EXCLUSIVE_SPINNERS)
1116                 printf(" with exclusive spinners pending\n");
1117
1118         STACK_PRINT(lk);
1119 }
1120
1121 int
1122 lockstatus(struct lock *lk)
1123 {
1124         uintptr_t v, x;
1125         int ret;
1126
1127         ret = LK_SHARED;
1128         x = lk->lk_lock;
1129         v = LK_HOLDER(x);
1130
1131         if ((x & LK_SHARE) == 0) {
1132                 if (v == (uintptr_t)curthread || v == LK_KERNPROC)
1133                         ret = LK_EXCLUSIVE;
1134                 else
1135                         ret = LK_EXCLOTHER;
1136         } else if (x == LK_UNLOCKED)
1137                 ret = 0;
1138
1139         return (ret);
1140 }
1141
1142 #ifdef INVARIANT_SUPPORT
1143 #ifndef INVARIANTS
1144 #undef  _lockmgr_assert
1145 #endif
1146
1147 void
1148 _lockmgr_assert(struct lock *lk, int what, const char *file, int line)
1149 {
1150         int slocked = 0;
1151
1152         if (panicstr != NULL)
1153                 return;
1154         switch (what) {
1155         case KA_SLOCKED:
1156         case KA_SLOCKED | KA_NOTRECURSED:
1157         case KA_SLOCKED | KA_RECURSED:
1158                 slocked = 1;
1159         case KA_LOCKED:
1160         case KA_LOCKED | KA_NOTRECURSED:
1161         case KA_LOCKED | KA_RECURSED:
1162 #ifdef WITNESS
1163
1164                 /*
1165                  * We cannot trust WITNESS if the lock is held in exclusive
1166                  * mode and a call to lockmgr_disown() happened.
1167                  * Workaround this skipping the check if the lock is held in
1168                  * exclusive mode even for the KA_LOCKED case.
1169                  */
1170                 if (slocked || (lk->lk_lock & LK_SHARE)) {
1171                         witness_assert(&lk->lock_object, what, file, line);
1172                         break;
1173                 }
1174 #endif
1175                 if (lk->lk_lock == LK_UNLOCKED ||
1176                     ((lk->lk_lock & LK_SHARE) == 0 && (slocked ||
1177                     (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk)))))
1178                         panic("Lock %s not %slocked @ %s:%d\n",
1179                             lk->lock_object.lo_name, slocked ? "share" : "",
1180                             file, line);
1181
1182                 if ((lk->lk_lock & LK_SHARE) == 0) {
1183                         if (lockmgr_recursed(lk)) {
1184                                 if (what & KA_NOTRECURSED)
1185                                         panic("Lock %s recursed @ %s:%d\n",
1186                                             lk->lock_object.lo_name, file,
1187                                             line);
1188                         } else if (what & KA_RECURSED)
1189                                 panic("Lock %s not recursed @ %s:%d\n",
1190                                     lk->lock_object.lo_name, file, line);
1191                 }
1192                 break;
1193         case KA_XLOCKED:
1194         case KA_XLOCKED | KA_NOTRECURSED:
1195         case KA_XLOCKED | KA_RECURSED:
1196                 if (!lockmgr_xlocked(lk) && !lockmgr_disowned(lk))
1197                         panic("Lock %s not exclusively locked @ %s:%d\n",
1198                             lk->lock_object.lo_name, file, line);
1199                 if (lockmgr_recursed(lk)) {
1200                         if (what & KA_NOTRECURSED)
1201                                 panic("Lock %s recursed @ %s:%d\n",
1202                                     lk->lock_object.lo_name, file, line);
1203                 } else if (what & KA_RECURSED)
1204                         panic("Lock %s not recursed @ %s:%d\n",
1205                             lk->lock_object.lo_name, file, line);
1206                 break;
1207         case KA_UNLOCKED:
1208                 if (lockmgr_xlocked(lk) || lockmgr_disowned(lk))
1209                         panic("Lock %s exclusively locked @ %s:%d\n",
1210                             lk->lock_object.lo_name, file, line);
1211                 break;
1212         default:
1213                 panic("Unknown lockmgr assertion: %d @ %s:%d\n", what, file,
1214                     line);
1215         }
1216 }
1217 #endif
1218
1219 #ifdef DDB
1220 int
1221 lockmgr_chain(struct thread *td, struct thread **ownerp)
1222 {
1223         struct lock *lk;
1224
1225         lk = td->td_wchan;
1226
1227         if (LOCK_CLASS(&lk->lock_object) != &lock_class_lockmgr)
1228                 return (0);
1229         db_printf("blocked on lockmgr %s", lk->lock_object.lo_name);
1230         if (lk->lk_lock & LK_SHARE)
1231                 db_printf("SHARED (count %ju)\n",
1232                     (uintmax_t)LK_SHARERS(lk->lk_lock));
1233         else
1234                 db_printf("EXCL\n");
1235         *ownerp = lockmgr_xholder(lk);
1236
1237         return (1);
1238 }
1239
1240 static void
1241 db_show_lockmgr(struct lock_object *lock)
1242 {
1243         struct thread *td;
1244         struct lock *lk;
1245
1246         lk = (struct lock *)lock;
1247
1248         db_printf(" state: ");
1249         if (lk->lk_lock == LK_UNLOCKED)
1250                 db_printf("UNLOCKED\n");
1251         else if (lk->lk_lock & LK_SHARE)
1252                 db_printf("SLOCK: %ju\n", (uintmax_t)LK_SHARERS(lk->lk_lock));
1253         else {
1254                 td = lockmgr_xholder(lk);
1255                 if (td == (struct thread *)LK_KERNPROC)
1256                         db_printf("XLOCK: LK_KERNPROC\n");
1257                 else
1258                         db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td,
1259                             td->td_tid, td->td_proc->p_pid,
1260                             td->td_proc->p_comm);
1261                 if (lockmgr_recursed(lk))
1262                         db_printf(" recursed: %d\n", lk->lk_recurse);
1263         }
1264         db_printf(" waiters: ");
1265         switch (lk->lk_lock & LK_ALL_WAITERS) {
1266         case LK_SHARED_WAITERS:
1267                 db_printf("shared\n");
1268                 break;
1269         case LK_EXCLUSIVE_WAITERS:
1270                 db_printf("exclusive\n");
1271                 break;
1272         case LK_ALL_WAITERS:
1273                 db_printf("shared and exclusive\n");
1274                 break;
1275         default:
1276                 db_printf("none\n");
1277         }
1278         db_printf(" spinners: ");
1279         if (lk->lk_lock & LK_EXCLUSIVE_SPINNERS)
1280                 db_printf("exclusive\n");
1281         else
1282                 db_printf("none\n");
1283 }
1284 #endif