include/os/lock_private.h

   1 /*
   2  * Copyright (c) 2013-2016 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_APACHE_LICENSE_HEADER_START@
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  *
  18  * @APPLE_APACHE_LICENSE_HEADER_END@
  19  */
  20
  21 #ifndef __OS_LOCK_PRIVATE__
  22 #define __OS_LOCK_PRIVATE__
  23
  24 #include <Availability.h>
  25 #include <TargetConditionals.h>
  26 #include <sys/cdefs.h>
  27 #include <stddef.h>
  28 #include <stdint.h>
  29 #include <stdbool.h>
  30 #include <os/base_private.h>
  31 #include <os/lock.h>
  32
  33 OS_ASSUME_NONNULL_BEGIN
  34
  35 /*! @header
  36  * Low-level lock SPI
  37  */
  38
  39 #define OS_LOCK_SPI_VERSION 20160406
  40
  41 /*!
  42  * @typedef os_lock_t
  43  *
  44  * @abstract
  45  * Pointer to one of the os_lock variants.
  46  */
  47
  48 #define OS_LOCK_TYPE_STRUCT(type) const struct _os_lock_type_##type##_s
  49 #define OS_LOCK_TYPE_REF(type) _os_lock_type_##type
  50 #define OS_LOCK_TYPE_DECL(type) OS_LOCK_TYPE_STRUCT(type) OS_LOCK_TYPE_REF(type)
  51
  52 #define OS_LOCK(type) os_lock_##type##_s
  53 #define OS_LOCK_STRUCT(type) struct OS_LOCK(type)
  54
  55 #if defined(__cplusplus) && __cplusplus >= 201103L
  56
  57 #define OS_LOCK_DECL(type, size) \
  58                 typedef OS_LOCK_STRUCT(type) : public OS_LOCK(base) { \
  59                         private: \
  60                         OS_LOCK_TYPE_STRUCT(type) * const osl_type OS_UNUSED; \
  61                         uintptr_t _osl_##type##_opaque[size-1] OS_UNUSED; \
  62                         public: \
  63             constexpr OS_LOCK(type)() : \
  64                                 osl_type(&OS_LOCK_TYPE_REF(type)), _osl_##type##_opaque() {} \
  65                 } OS_LOCK(type)
  66 #define OS_LOCK_INIT(type) {}
  67
  68 typedef OS_LOCK_STRUCT(base) {
  69         protected:
  70         constexpr OS_LOCK(base)() {}
  71 } *os_lock_t;
  72
  73 #else
  74
  75 #define OS_LOCK_DECL(type, size) \
  76                 typedef OS_LOCK_STRUCT(type) { \
  77                         OS_LOCK_TYPE_STRUCT(type) * const osl_type; \
  78                         uintptr_t _osl_##type##_opaque[size-1]; \
  79                 } OS_LOCK(type)
  80
  81 #define OS_LOCK_INIT(type) { .osl_type = &OS_LOCK_TYPE_REF(type), }
  82
  83 #ifndef OS_LOCK_T_MEMBER
  84 #define OS_LOCK_T_MEMBER(type) OS_LOCK_STRUCT(type) *_osl_##type
  85 #endif
  86
  87 typedef OS_TRANSPARENT_UNION union {
  88         OS_LOCK_T_MEMBER(base);
  89         OS_LOCK_T_MEMBER(unfair);
  90         OS_LOCK_T_MEMBER(nospin);
  91         OS_LOCK_T_MEMBER(spin);
  92         OS_LOCK_T_MEMBER(handoff);
  93         OS_LOCK_T_MEMBER(eliding);
  94         OS_LOCK_T_MEMBER(transactional);
  95 } os_lock_t;
  96
  97 #endif
  98
  99 /*!
 100  * @typedef os_lock_unfair_s
 101  *
 102  * @abstract
 103  * os_lock variant equivalent to os_unfair_lock. Does not spin on contention but
 104  * waits in the kernel to be woken up by an unlock. The lock value contains
 105  * ownership information that the system may use to attempt to resolve priority
 106  * inversions.
 107  *
 108  * @discussion
 109  * Intended as a replacement for os_lock_spin_s or OSSpinLock. Like with
 110  * OSSpinLock there is no attempt at fairness or lock ordering, e.g. an unlocker
 111  * can potentially immediately reacquire the lock before a woken up waiter gets
 112  * an opportunity to attempt to acquire the lock, so starvation is possibile.
 113  *
 114  * Must be initialized with OS_LOCK_UNFAIR_INIT
 115  */
 116 __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0)
 117 __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0)
 118 OS_EXPORT OS_LOCK_TYPE_DECL(unfair);
 119 OS_LOCK_DECL(unfair, 2);
 120 #define OS_LOCK_UNFAIR_INIT OS_LOCK_INIT(unfair)
 121
 122 /*!
 123  * @typedef os_lock_nospin_s
 124  *
 125  * @abstract
 126  * os_lock variant that does not spin on contention but waits in the kernel to
 127  * be woken up by an unlock. No attempt to resolve priority inversions is made
 128  * so os_unfair_lock or os_lock_unfair_s should generally be preferred.
 129  *
 130  * @discussion
 131  * Intended as a replacement for os_lock_spin_s or OSSpinLock. Like with
 132  * OSSpinLock there is no attempt at fairness or lock ordering, e.g. an unlocker
 133  * can potentially immediately reacquire the lock before a woken up waiter gets
 134  * an opportunity to attempt to acquire the lock, so starvation is possibile.
 135  *
 136  * Must be initialized with OS_LOCK_NOSPIN_INIT
 137  */
 138 __OSX_AVAILABLE(10.12) __IOS_AVAILABLE(10.0)
 139 __TVOS_AVAILABLE(10.0) __WATCHOS_AVAILABLE(3.0)
 140 OS_EXPORT OS_LOCK_TYPE_DECL(nospin);
 141 OS_LOCK_DECL(nospin, 2);
 142 #define OS_LOCK_NOSPIN_INIT OS_LOCK_INIT(nospin)
 143
 144 /*!
 145  * @typedef os_lock_spin_s
 146  *
 147  * @abstract
 148  * Deprecated os_lock variant that on contention starts by spinning trying to
 149  * acquire the lock, then depressing the priority of the current thread and
 150  * finally blocking the thread waiting for the lock to become available.
 151  * Equivalent to OSSpinLock and equally not recommended, see discussion in
 152  * libkern/OSAtomic.h headerdoc.
 153  *
 154  * @discussion
 155  * Spinlocks are intended to be held only for very brief periods of time. The
 156  * critical section must not make syscalls and should avoid touching areas of
 157  * memory that may trigger a page fault, in particular if the critical section
 158  * may be executing on threads of widely differing priorities or on a mix of
 159  * IO-throttled and unthrottled threads.
 160  *
 161  * Must be initialized with OS_LOCK_SPIN_INIT
 162  */
 163 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_7_0)
 164 OS_EXPORT OS_LOCK_TYPE_DECL(spin);
 165 OS_LOCK_DECL(spin, 2);
 166 #define OS_LOCK_SPIN_INIT OS_LOCK_INIT(spin)
 167
 168 /*!
 169  * @typedef os_lock_handoff_s
 170  *
 171  * @abstract
 172  * os_lock variant that on contention hands off the current kernel thread to the
 173  * lock-owning userspace thread (if it is not running), temporarily overriding
 174  * its priority and IO throttle if necessary.
 175  *
 176  * @discussion
 177  * Intended for use in limited circumstances where the critical section might
 178  * be executing on threads of widely differing priorities or on a mix of
 179  * IO-throttled and unthrottled threads where the ordinary os_lock_spin_s would
 180  * be likely to encounter a priority inversion.
 181  *
 182  * IMPORTANT: This lock variant is NOT intended as a general replacement for all
 183  * uses of os_lock_spin_s or OSSpinLock.
 184  *
 185  * Must be initialized with OS_LOCK_HANDOFF_INIT
 186  */
 187 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_7_0)
 188 OS_EXPORT OS_LOCK_TYPE_DECL(handoff);
 189 OS_LOCK_DECL(handoff, 2);
 190 #define OS_LOCK_HANDOFF_INIT OS_LOCK_INIT(handoff)
 191
 192
 193 #if !TARGET_OS_IPHONE
 194 /*!
 195  * @typedef os_lock_eliding_s
 196  *
 197  * @abstract
 198  * os_lock variant that uses hardware lock elision support if available to allow
 199  * multiple processors to concurrently execute a critical section as long as
 200  * they don't perform conflicting operations on each other's data. In case of
 201  * conflict, the lock reverts to exclusive operation and os_lock_spin_s behavior
 202  * on contention (at potential extra cost for the aborted attempt at lock-elided
 203  * concurrent execution). If hardware HLE support is not present, this lock
 204  * variant behaves like os_lock_spin_s.
 205  *
 206  * @discussion
 207  * IMPORTANT: Use of this lock variant MUST be extensively tested on hardware
 208  * with HLE support to ensure the data access pattern and length of the critical
 209  * section allows lock-elided execution to succeed frequently enough to offset
 210  * the cost of any aborted concurrent execution.
 211  *
 212  * Must be initialized with OS_LOCK_ELIDING_INIT
 213  */
 214 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_NA)
 215 OS_EXPORT OS_LOCK_TYPE_DECL(eliding);
 216 OS_LOCK_DECL(eliding, 8) OS_ALIGNED(64);
 217 #define OS_LOCK_ELIDING_INIT OS_LOCK_INIT(eliding)
 218
 219 /*!
 220  * @typedef os_lock_transactional_s
 221  *
 222  * @abstract
 223  * os_lock variant that uses hardware restricted transactional memory support if
 224  * available to allow multiple processors to concurrently execute the critical
 225  * section as a transactional region. If transactional execution aborts, the
 226  * lock reverts to exclusive operation and os_lock_spin_s behavior on contention
 227  * (at potential extra cost for the aborted attempt at transactional concurrent
 228  * execution). If hardware RTM support is not present, this lock variant behaves
 229  * like os_lock_eliding_s.
 230  *
 231  * @discussion
 232  * IMPORTANT: Use of this lock variant MUST be extensively tested on hardware
 233  * with RTM support to ensure the data access pattern and length of the critical
 234  * section allows transactional execution to succeed frequently enough to offset
 235  * the cost of any aborted transactions.
 236  *
 237  * Must be initialized with OS_LOCK_TRANSACTIONAL_INIT
 238  */
 239 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_NA)
 240 OS_EXPORT OS_LOCK_TYPE_DECL(transactional);
 241 OS_LOCK_DECL(transactional, 8) OS_ALIGNED(64);
 242 #define OS_LOCK_TRANSACTIONAL_INIT OS_LOCK_INIT(transactional)
 243 #endif
 244
 245 __BEGIN_DECLS
 246
 247 /*!
 248  * @function os_lock_lock
 249  *
 250  * @abstract
 251  * Locks an os_lock variant.
 252  *
 253  * @param lock
 254  * Pointer to one of the os_lock variants.
 255  */
 256 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_7_0)
 257 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 258 void os_lock_lock(os_lock_t lock);
 259
 260 /*!
 261  * @function os_lock_trylock
 262  *
 263  * @abstract
 264  * Locks an os_lock variant if it is not already locked.
 265  *
 266  * @param lock
 267  * Pointer to one of the os_lock variants.
 268  *
 269  * @result
 270  * Returns true if the lock was succesfully locked and false if the lock was
 271  * already locked.
 272  */
 273 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_7_0)
 274 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 275 bool os_lock_trylock(os_lock_t lock);
 276
 277 /*!
 278  * @function os_lock_unlock
 279  *
 280  * @abstract
 281  * Unlocks an os_lock variant.
 282  *
 283  * @param lock
 284  * Pointer to one of the os_lock variants.
 285  */
 286 __OSX_AVAILABLE_STARTING(__MAC_10_9,__IPHONE_7_0)
 287 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 288 void os_lock_unlock(os_lock_t lock);
 289
 290 /*! @group os_unfair_lock SPI
 291  *
 292  * @abstract
 293  * Replacement for the deprecated OSSpinLock. Does not spin on contention but
 294  * waits in the kernel to be woken up by an unlock. The opaque lock value
 295  * contains thread ownership information that the system may use to attempt to
 296  * resolve priority inversions.
 297  *
 298  * This lock must be unlocked from the same thread that locked it, attemps to
 299  * unlock from a different thread will cause an assertion aborting the process.
 300  *
 301  * This lock must not be accessed from multiple processes or threads via shared
 302  * or multiply-mapped memory, the lock implementation relies on the address of
 303  * the lock value and owning process.
 304  *
 305  * @discussion
 306  * As with OSSpinLock there is no attempt at fairness or lock ordering, e.g. an
 307  * unlocker can potentially immediately reacquire the lock before a woken up
 308  * waiter gets an opportunity to attempt to acquire the lock. This may be
 309  * advantageous for performance reasons, but also makes starvation of waiters a
 310  * possibility.
 311  *
 312  * Must be initialized with OS_UNFAIR_LOCK_INIT
 313  */
 314
 315 /*!
 316  * @typedef os_unfair_lock_options_t
 317  *
 318  * @const OS_UNFAIR_LOCK_DATA_SYNCHRONIZATION
 319  * This flag informs the runtime that the specified lock is used for data
 320  * synchronization and that the lock owner is always able to make progress
 321  * toward releasing the lock without the help of another thread in the same
 322  * process. This hint will cause the workqueue subsystem to not create new
 323  * threads to offset for threads waiting for the lock.
 324  *
 325  * When this flag is used, the code running under the critical section should
 326  * be well known and under your control  (Generally it should not call into
 327  * framework code).
 328  */
 329 OS_ENUM(os_unfair_lock_options, uint32_t,
 330         OS_UNFAIR_LOCK_NONE
 331                 OS_UNFAIR_LOCK_AVAILABILITY = 0x00000000,
 332         OS_UNFAIR_LOCK_DATA_SYNCHRONIZATION
 333                 OS_UNFAIR_LOCK_AVAILABILITY = 0x00010000,
 334 );
 335
 336 /*!
 337  * @function os_unfair_lock_lock_with_options
 338  *
 339  * @abstract
 340  * Locks an os_unfair_lock.
 341  *
 342  * @param lock
 343  * Pointer to an os_unfair_lock.
 344  *
 345  * @param options
 346  * Options to alter the behavior of the lock. See os_unfair_lock_options_t.
 347  */
 348 OS_UNFAIR_LOCK_AVAILABILITY
 349 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 350 void os_unfair_lock_lock_with_options(os_unfair_lock_t lock,
 351                 os_unfair_lock_options_t options);
 352
 353 /*!
 354  * @function os_unfair_lock_assert_owner
 355  *
 356  * @abstract
 357  * Asserts that the calling thread is the current owner of the specified
 358  * unfair lock.
 359  *
 360  * @discussion
 361  * If the lock is currently owned by the calling thread, this function returns.
 362  *
 363  * If the lock is unlocked or owned by a different thread, this function
 364  * asserts and terminates the process.
 365  *
 366  * @param lock
 367  * Pointer to an os_unfair_lock.
 368  */
 369 OS_UNFAIR_LOCK_AVAILABILITY
 370 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 371 void os_unfair_lock_assert_owner(os_unfair_lock_t lock);
 372
 373 /*!
 374  * @function os_unfair_lock_assert_not_owner
 375  *
 376  * @abstract
 377  * Asserts that the calling thread is not the current owner of the specified
 378  * unfair lock.
 379  *
 380  * @discussion
 381  * If the lock is unlocked or owned by a different thread, this function
 382  * returns.
 383  *
 384  * If the lock is currently owned by the current thread, this function asserts
 385  * and terminates the process.
 386  *
 387  * @param lock
 388  * Pointer to an os_unfair_lock.
 389  */
 390 OS_UNFAIR_LOCK_AVAILABILITY
 391 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 392 void os_unfair_lock_assert_not_owner(os_unfair_lock_t lock);
 393
 394 /*! @group os_unfair_lock variant for consumption by Libc
 395  */
 396 OS_UNFAIR_LOCK_AVAILABILITY
 397 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 398 void os_unfair_lock_lock_with_options_4Libc(os_unfair_lock_t lock,
 399                 os_unfair_lock_options_t options);
 400
 401 OS_UNFAIR_LOCK_AVAILABILITY
 402 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 403 void os_unfair_lock_unlock_4Libc(os_unfair_lock_t lock);
 404
 405 __END_DECLS
 406
 407 OS_ASSUME_NONNULL_END
 408
 409 /*! @group Inline os_unfair_lock interfaces
 410  *
 411  * Inline versions of the os_unfair_lock fastpath.
 412  *
 413  * Intended exclusively for special highly performance-sensitive cases where the
 414  * function calls to the os_unfair_lock API entrypoints add measurable overhead.
 415  *
 416  * Do not use in frameworks to implement synchronization API primitives that are
 417  * exposed to developers, that would lead to false positives for that API from
 418  * tools such as ThreadSanitizer.
 419  *
 420  * !!!!!!!!!!!!!!!!!!!!! WARNING WARNING WARNING WARNING !!!!!!!!!!!!!!!!!!!!!
 421  * DO NOT USE IN CODE THAT IS NOT PART OF THE OPERATING SYSTEM OR THAT IS NOT
 422  *          REBUILT AS PART OF AN OS WORLDBUILD. YOU HAVE BEEN WARNED!
 423  * !!!!!!!!!!!!!!!!!!!!! WARNING WARNING WARNING WARNING !!!!!!!!!!!!!!!!!!!!!
 424  *
 425  * Define OS_UNFAIR_LOCK_INLINE=1 to indicate that you have read the warning
 426  * above and still wish to use these interfaces.
 427  */
 428
 429 #if defined(OS_UNFAIR_LOCK_INLINE) && OS_UNFAIR_LOCK_INLINE
 430
 431 #include <pthread/tsd_private.h>
 432
 433 #ifdef __cplusplus
 434 extern "C++" {
 435 #if !(__has_include(<atomic>) && __has_feature(cxx_atomic))
 436 #error Cannot use inline os_unfair_lock without <atomic> and C++11 atomics
 437 #endif
 438 #include <atomic>
 439 typedef std::atomic<os_unfair_lock> _os_atomic_unfair_lock;
 440 #define OSLOCK_STD(_a) std::_a
 441 __BEGIN_DECLS
 442 #else
 443 #if !(__has_include(<stdatomic.h>) && __has_extension(c_atomic))
 444 #error Cannot use inline os_unfair_lock without <stdatomic.h> and C11 atomics
 445 #endif
 446 #include <stdatomic.h>
 447 typedef _Atomic(os_unfair_lock) _os_atomic_unfair_lock;
 448 #define OSLOCK_STD(_a) _a
 449 #endif
 450
 451 OS_ASSUME_NONNULL_BEGIN
 452
 453 /*!
 454  * @function os_unfair_lock_lock_inline
 455  *
 456  * @abstract
 457  * Locks an os_unfair_lock.
 458  *
 459  * @param lock
 460  * Pointer to an os_unfair_lock.
 461  */
 462 OS_UNFAIR_LOCK_AVAILABILITY
 463 OS_INLINE OS_ALWAYS_INLINE OS_NONNULL_ALL
 464 void
 465 os_unfair_lock_lock_inline(os_unfair_lock_t lock)
 466 {
 467         if (!_pthread_has_direct_tsd()) return os_unfair_lock_lock(lock);
 468         uintptr_t mts = (uintptr_t)_pthread_getspecific_direct(
 469                         _PTHREAD_TSD_SLOT_MACH_THREAD_SELF);
 470         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 471         if (!OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 472                         (_os_atomic_unfair_lock*)lock, &unlocked, locked,
 473                         OSLOCK_STD(memory_order_acquire),
 474                         OSLOCK_STD(memory_order_relaxed))) {
 475                 return os_unfair_lock_lock(lock);
 476         }
 477 }
 478
 479 /*!
 480  * @function os_unfair_lock_lock_with_options_inline
 481  *
 482  * @abstract
 483  * Locks an os_unfair_lock.
 484  *
 485  * @param lock
 486  * Pointer to an os_unfair_lock.
 487  *
 488  * @param options
 489  * Options to alter the behavior of the lock. See os_unfair_lock_options_t.
 490  */
 491 OS_UNFAIR_LOCK_AVAILABILITY
 492 OS_INLINE OS_ALWAYS_INLINE OS_NONNULL_ALL
 493 void
 494 os_unfair_lock_lock_with_options_inline(os_unfair_lock_t lock,
 495                 os_unfair_lock_options_t options)
 496 {
 497         if (!_pthread_has_direct_tsd()) {
 498                 return os_unfair_lock_lock_with_options(lock, options);
 499         }
 500         uintptr_t mts = (uintptr_t)_pthread_getspecific_direct(
 501                         _PTHREAD_TSD_SLOT_MACH_THREAD_SELF);
 502         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 503         if (!OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 504                         (_os_atomic_unfair_lock*)lock, &unlocked, locked,
 505                         OSLOCK_STD(memory_order_acquire),
 506                         OSLOCK_STD(memory_order_relaxed))) {
 507                 return os_unfair_lock_lock_with_options(lock, options);
 508         }
 509 }
 510
 511 /*!
 512  * @function os_unfair_lock_trylock_inline
 513  *
 514  * @abstract
 515  * Locks an os_unfair_lock if it is not already locked.
 516  *
 517  * @discussion
 518  * It is invalid to surround this function with a retry loop, if this function
 519  * returns false, the program must be able to proceed without having acquired
 520  * the lock, or it must call os_unfair_lock_lock_inline() instead.
 521  *
 522  * @param lock
 523  * Pointer to an os_unfair_lock.
 524  *
 525  * @result
 526  * Returns true if the lock was succesfully locked and false if the lock was
 527  * already locked.
 528  */
 529 OS_UNFAIR_LOCK_AVAILABILITY
 530 OS_INLINE OS_ALWAYS_INLINE OS_WARN_RESULT OS_NONNULL_ALL
 531 bool
 532 os_unfair_lock_trylock_inline(os_unfair_lock_t lock)
 533 {
 534         if (!_pthread_has_direct_tsd()) return os_unfair_lock_trylock(lock);
 535         uintptr_t mts = (uintptr_t)_pthread_getspecific_direct(
 536                         _PTHREAD_TSD_SLOT_MACH_THREAD_SELF);
 537         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 538         return OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 539                         (_os_atomic_unfair_lock*)lock, &unlocked, locked,
 540                         OSLOCK_STD(memory_order_acquire), OSLOCK_STD(memory_order_relaxed));
 541 }
 542
 543 /*!
 544  * @function os_unfair_lock_unlock_inline
 545  *
 546  * @abstract
 547  * Unlocks an os_unfair_lock.
 548  *
 549  * @param lock
 550  * Pointer to an os_unfair_lock.
 551  */
 552 OS_UNFAIR_LOCK_AVAILABILITY
 553 OS_INLINE OS_ALWAYS_INLINE OS_NONNULL_ALL
 554 void
 555 os_unfair_lock_unlock_inline(os_unfair_lock_t lock)
 556 {
 557         if (!_pthread_has_direct_tsd()) return os_unfair_lock_unlock(lock);
 558         uintptr_t mts = (uintptr_t)_pthread_getspecific_direct(
 559                         _PTHREAD_TSD_SLOT_MACH_THREAD_SELF);
 560         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 561         if (!OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 562                         (_os_atomic_unfair_lock*)lock, &locked, unlocked,
 563                         OSLOCK_STD(memory_order_release),
 564                         OSLOCK_STD(memory_order_relaxed))) {
 565                 return os_unfair_lock_unlock(lock);
 566         }
 567 }
 568
 569 /*! @group os_unfair_lock no-TSD interfaces
 570  *
 571  * Like the above, but don't require being on a thread with valid TSD, so they
 572  * can be called from injected mach-threads.  The normal routines use the TSD
 573  * value for mach_thread_self(), these routines use MACH_PORT_DEAD for the
 574  * locked value instead.  As a result, they will be unable to resolve priority
 575  * inversions.
 576  *
 577  * This should only be used by libpthread.
 578  *
 579  */
 580 OS_UNFAIR_LOCK_AVAILABILITY
 581 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 582 void os_unfair_lock_lock_no_tsd_4libpthread(os_unfair_lock_t lock);
 583
 584 OS_UNFAIR_LOCK_AVAILABILITY
 585 OS_EXPORT OS_NOTHROW OS_NONNULL_ALL
 586 void os_unfair_lock_unlock_no_tsd_4libpthread(os_unfair_lock_t lock);
 587
 588 /*!
 589  * @function os_unfair_lock_lock_inline_no_tsd_4libpthread
 590  *
 591  * @abstract
 592  * Locks an os_unfair_lock, without requiring valid TSD.
 593  *
 594  * This should only be used by libpthread.
 595  *
 596  * @param lock
 597  * Pointer to an os_unfair_lock.
 598  */
 599 OS_UNFAIR_LOCK_AVAILABILITY
 600 OS_INLINE OS_ALWAYS_INLINE OS_NONNULL_ALL
 601 void
 602 os_unfair_lock_lock_inline_no_tsd_4libpthread(os_unfair_lock_t lock)
 603 {
 604         uintptr_t mts = (uintptr_t)MACH_PORT_DEAD;
 605         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 606         if (!OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 607                         (_os_atomic_unfair_lock*)lock, &unlocked, locked,
 608                         OSLOCK_STD(memory_order_acquire),
 609                         OSLOCK_STD(memory_order_relaxed))) {
 610                 return os_unfair_lock_lock_no_tsd_4libpthread(lock);
 611         }
 612 }
 613
 614 /*!
 615  * @function os_unfair_lock_unlock_inline_no_tsd_4libpthread
 616  *
 617  * @abstract
 618  * Unlocks an os_unfair_lock, without requiring valid TSD.
 619  *
 620  * This should only be used by libpthread.
 621  *
 622  * @param lock
 623  * Pointer to an os_unfair_lock.
 624  */
 625 OS_UNFAIR_LOCK_AVAILABILITY
 626 OS_INLINE OS_ALWAYS_INLINE OS_NONNULL_ALL
 627 void
 628 os_unfair_lock_unlock_inline_no_tsd_4libpthread(os_unfair_lock_t lock)
 629 {
 630         uintptr_t mts = (uintptr_t)MACH_PORT_DEAD;
 631         os_unfair_lock unlocked = OS_UNFAIR_LOCK_INIT, locked = { mts };
 632         if (!OSLOCK_STD(atomic_compare_exchange_strong_explicit)(
 633                         (_os_atomic_unfair_lock*)lock, &locked, unlocked,
 634                         OSLOCK_STD(memory_order_release),
 635                         OSLOCK_STD(memory_order_relaxed))) {
 636                 return os_unfair_lock_unlock_no_tsd_4libpthread(lock);
 637         }
 638 }
 639
 640 OS_ASSUME_NONNULL_END
 641
 642 #undef OSLOCK_STD
 643 #ifdef __cplusplus
 644 __END_DECLS
 645 } // extern "C++"
 646 #endif
 647
 648 #endif // OS_UNFAIR_LOCK_INLINE
 649
 650 #endif // __OS_LOCK_PRIVATE__