1//===-- Implementation of pthread_spin_unlock function --------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/pthread/pthread_spin_unlock.h"
10#include "hdr/errno_macros.h"
11#include "src/__support/common.h"
12#include "src/__support/threads/identifier.h"
13#include "src/__support/threads/spin_lock.h"
14
15namespace LIBC_NAMESPACE_DECL {
16
17static_assert(sizeof(pthread_spinlock_t::__lockword) == sizeof(SpinLock) &&
18 alignof(decltype(pthread_spinlock_t::__lockword)) ==
19 alignof(SpinLock),
20 "pthread_spinlock_t::__lockword and SpinLock must be of the same "
21 "size and alignment");
22
23LLVM_LIBC_FUNCTION(int, pthread_spin_unlock, (pthread_spinlock_t * lock)) {
24 // If an implementation detects that the value specified by the lock argument
25 // to pthread_spin_lock() or pthread_spin_trylock() does not refer to an
26 // initialized spin lock object, it is recommended that the function should
27 // fail and report an [EINVAL] error.
28 if (!lock)
29 return EINVAL;
30 auto spin_lock = reinterpret_cast<SpinLock *>(&lock->__lockword);
31 if (!spin_lock || spin_lock->is_invalid())
32 return EINVAL;
33 // If an implementation detects that the value specified by the lock argument
34 // to pthread_spin_unlock() refers to a spin lock object for which the current
35 // thread does not hold the lock, it is recommended that the function should
36 // fail and report an [EPERM] error.
37 if (lock->__owner != internal::gettid())
38 return EPERM;
39 // Release the lock.
40 lock->__owner = 0;
41 spin_lock->unlock();
42 return 0;
43}
44} // namespace LIBC_NAMESPACE_DECL
45

source code of libc/src/pthread/pthread_spin_unlock.cpp