53 lines · cpp
1//===-- condition_variable_linux.cpp ----------------------------*- C++ -*-===//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-exception6//7//===----------------------------------------------------------------------===//8 9#include "platform.h"10 11#if SCUDO_LINUX12 13#include "condition_variable_linux.h"14 15#include "atomic_helpers.h"16 17#include <limits.h>18#include <linux/futex.h>19#include <sys/syscall.h>20#include <unistd.h>21 22namespace scudo {23 24void ConditionVariableLinux::notifyAllImpl(UNUSED HybridMutex &M) {25 const u32 V = atomic_load_relaxed(&Counter);26 atomic_store_relaxed(&Counter, V + 1);27 28 // TODO(chiahungduan): Move the waiters from the futex waiting queue29 // `Counter` to futex waiting queue `M` so that the awoken threads won't be30 // blocked again due to locked `M` by current thread.31 if (LastNotifyAll != V) {32 syscall(SYS_futex, reinterpret_cast<uptr>(&Counter), FUTEX_WAKE_PRIVATE,33 INT_MAX, nullptr, nullptr, 0);34 }35 36 LastNotifyAll = V + 1;37}38 39void ConditionVariableLinux::waitImpl(HybridMutex &M) {40 const u32 V = atomic_load_relaxed(&Counter) + 1;41 atomic_store_relaxed(&Counter, V);42 43 // TODO: Use ScopedUnlock when it's supported.44 M.unlock();45 syscall(SYS_futex, reinterpret_cast<uptr>(&Counter), FUTEX_WAIT_PRIVATE, V,46 nullptr, nullptr, 0);47 M.lock();48}49 50} // namespace scudo51 52#endif // SCUDO_LINUX53