bionic_futex.h revision ced906c849704f379d7191822f6d74993d4fa296 
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
38__BEGIN_DECLS
39
40struct timespec;
41
42static inline int __futex(volatile void* ftx, int op, int value, const struct timespec* timeout) {
43  // Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
44  int saved_errno = errno;
45  if (syscall(__NR_futex, ftx, op, value, timeout) == 0) {
46    return 0;
47  }
48  int result = -errno;
49  errno = saved_errno;
50  return result;
51}
52
53static inline int __futex_wake(volatile void* ftx, int count) {
54  return __futex(ftx, FUTEX_WAKE, count, NULL);
55}
56
57static inline int __futex_wake_ex(volatile void* ftx, bool shared, int count) {
58  return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL);
59}
60
61static inline int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
62  return __futex(ftx, FUTEX_WAIT, value, timeout);
63}
64
65static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value, const struct timespec* timeout) {
66  return __futex(ftx, shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE, value, timeout);
67}
68
69__END_DECLS
70
71#endif /* _BIONIC_FUTEX_H */
72