1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28#ifndef _BIONIC_FUTEX_H
29#define _BIONIC_FUTEX_H
30
31#include <errno.h>
32#include <linux/futex.h>
33#include <stdbool.h>
34#include <stddef.h>
35#include <sys/cdefs.h>
36#include <sys/syscall.h>
37#include <unistd.h>
38
39__BEGIN_DECLS
40
41struct timespec;
42
43static inline __always_inline int __futex(volatile void* ftx, int op, int value,
44                                          const struct timespec* timeout,
45                                          int bitset) {
46  // Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
47  int saved_errno = errno;
48  int result = syscall(__NR_futex, ftx, op, value, timeout, NULL, bitset);
49  if (__predict_false(result == -1)) {
50    result = -errno;
51    errno = saved_errno;
52  }
53  return result;
54}
55
56static inline int __futex_wake(volatile void* ftx, int count) {
57  return __futex(ftx, FUTEX_WAKE, count, NULL, 0);
58}
59
60static inline int __futex_wake_ex(volatile void* ftx, bool shared, int count) {
61  return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL, 0);
62}
63
64static inline int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
65  return __futex(ftx, FUTEX_WAIT, value, timeout, 0);
66}
67
68static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value,
69                                  bool use_realtime_clock, const struct timespec* abs_timeout) {
70  return __futex(ftx, (shared ? FUTEX_WAIT_BITSET : FUTEX_WAIT_BITSET_PRIVATE) |
71                 (use_realtime_clock ? FUTEX_CLOCK_REALTIME : 0), value, abs_timeout,
72                 FUTEX_BITSET_MATCH_ANY);
73}
74
75__END_DECLS
76
77#endif /* _BIONIC_FUTEX_H */
78