[libc] add spin lock family functions (#100509)

This PR:
- add entrypoints for `pthread_spin_*`
- additionally, the fixes a typo that has been disabling lock related
tests

1 files changed, 47 insertions, 0 deletions

diff --git a/libc/src/pthread/pthread_spin_destroy.cpp b/libc/src/pthread/pthread_spin_destroy.cpp
new file mode 100644
index 000000000000..7d93dd967afe
--- /dev/null
+++ b/libc/src/pthread/pthread_spin_destroy.cpp
@@ -0,0 +1,47 @@
+//===-- Implementation of pthread_spin_destroy function -------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_spin_destroy.h"
+#include "hdr/errno_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/threads/spin_lock.h"
+namespace LIBC_NAMESPACE_DECL {
+
+static_assert(sizeof(pthread_spinlock_t::__lockword) == sizeof(SpinLock) &&
+                  alignof(decltype(pthread_spinlock_t::__lockword)) ==
+                      alignof(SpinLock),
+              "pthread_spinlock_t::__lockword and SpinLock must be of the same "
+              "size and alignment");
+
+LLVM_LIBC_FUNCTION(int, pthread_spin_destroy,
+                   ([[maybe_unused]] pthread_spinlock_t * lock)) {
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_lock() or pthread_spin_trylock() does not refer to an
+  // initialized spin lock object, it is recommended that the function should
+  // fail and report an [EINVAL] error.
+  if (!lock)
+    return EINVAL;
+  auto spin_lock = reinterpret_cast<SpinLock *>(&lock->__lockword);
+  if (!spin_lock || spin_lock->is_invalid())
+    return EINVAL;
+
+  // If an implementation detects that the value specified by the lock argument
+  // to pthread_spin_destroy() or pthread_spin_init() refers to a locked spin
+  // lock object, or detects that the value specified by the lock argument to
+  // pthread_spin_init() refers to an already initialized spin lock object, it
+  // is recommended that the function should fail and report an [EBUSY] error.
+  if (spin_lock->is_locked())
+    return EBUSY;
+
+  // poison the lock
+  spin_lock->~SpinLock();
+  lock->__owner = 0;
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL