1// Copyright (C) 2023 Intel Corporation.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#ifndef QFUTEX_LINUX_P_H
5#define QFUTEX_LINUX_P_H
6
7//
8// W A R N I N G
9// -------------
10//
11// This file is not part of the Qt API. It exists purely as an
12// implementation detail. This header file may change from version to
13// version without notice, or even be removed.
14//
15// We mean it.
16//
17
18#include <private/qcore_unix_p.h>
19#include <qdeadlinetimer.h>
20#include <qtsan_impl.h>
21
22#include <asm/unistd.h>
23#include <errno.h>
24#include <limits.h>
25#include <linux/futex.h>
26#include <sys/syscall.h>
27#include <unistd.h>
28
29// RISC-V does not supply __NR_futex
30#ifndef __NR_futex
31# define __NR_futex __NR_futex_time64
32#endif
33
34#define QT_ALWAYS_USE_FUTEX
35
36QT_BEGIN_NAMESPACE
37
38namespace QtLinuxFutex {
39constexpr inline bool futexAvailable() { return true; }
40
41inline long _q_futex(int *addr, int op, int val, quintptr val2 = 0,
42 int *addr2 = nullptr, int val3 = 0) noexcept
43{
44 QtTsan::futexRelease(addr, addr2);
45
46 // we use __NR_futex because some libcs (like Android's bionic) don't
47 // provide SYS_futex etc.
48 long result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
49
50 QtTsan::futexAcquire(addr, addr2);
51
52 return result;
53}
54template <typename T> int *addr(T *ptr)
55{
56 int *int_addr = reinterpret_cast<int *>(ptr);
57#if Q_BYTE_ORDER == Q_BIG_ENDIAN
58 if (sizeof(T) > sizeof(int))
59 int_addr++; //We want a pointer to the least significant half
60#endif
61 return int_addr;
62}
63
64template <typename Atomic>
65inline void futexWait(Atomic &futex, typename Atomic::Type expectedValue)
66{
67 _q_futex(addr(&futex), FUTEX_WAIT, qintptr(expectedValue));
68}
69template <typename Atomic>
70inline bool futexWait(Atomic &futex, typename Atomic::Type expectedValue, QDeadlineTimer deadline)
71{
72 auto timeout = deadline.deadline<std::chrono::steady_clock>().time_since_epoch();
73 struct timespec ts = durationToTimespec(timeout);
74 long r = _q_futex(addr(&futex), FUTEX_WAIT_BITSET, qintptr(expectedValue), quintptr(&ts),
75 nullptr, FUTEX_BITSET_MATCH_ANY);
76 return r == 0 || errno != ETIMEDOUT;
77}
78template <typename Atomic> inline void futexWakeOne(Atomic &futex)
79{
80 _q_futex(addr(&futex), FUTEX_WAKE, 1);
81}
82template <typename Atomic> inline void futexWakeAll(Atomic &futex)
83{
84 _q_futex(addr(&futex), FUTEX_WAKE, INT_MAX);
85}
86template <typename Atomic> inline
87void futexWakeOp(Atomic &futex1, int wake1, int wake2, Atomic &futex2, quint32 op)
88{
89 _q_futex(addr(&futex1), FUTEX_WAKE_OP, wake1, wake2, addr(&futex2), op);
90}} // namespace QtLinuxFutex
91namespace QtFutex = QtLinuxFutex;
92
93QT_END_NAMESPACE
94
95#endif // QFUTEX_LINUX_P_H
96

source code of qtbase/src/corelib/thread/qfutex_linux_p.h