futex.h revision 7ec681f3 
1/*
2 * Copyright © 2015 Intel
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24#ifndef UTIL_FUTEX_H
25#define UTIL_FUTEX_H
26
27#if defined(HAVE_LINUX_FUTEX_H)
28#define UTIL_FUTEX_SUPPORTED 1
29
30#include <limits.h>
31#include <stdint.h>
32#include <unistd.h>
33#include <linux/futex.h>
34#include <sys/syscall.h>
35#include <sys/time.h>
36
37static inline long sys_futex(void *addr1, int op, int val1, const struct timespec *timeout, void *addr2, int val3)
38{
39   return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
40}
41
42static inline int futex_wake(uint32_t *addr, int count)
43{
44   return sys_futex(addr, FUTEX_WAKE, count, NULL, NULL, 0);
45}
46
47static inline int futex_wait(uint32_t *addr, int32_t value, const struct timespec *timeout)
48{
49   /* FUTEX_WAIT_BITSET with FUTEX_BITSET_MATCH_ANY is equivalent to
50    * FUTEX_WAIT, except that it treats the timeout as absolute. */
51   return sys_futex(addr, FUTEX_WAIT_BITSET, value, timeout, NULL,
52                    FUTEX_BITSET_MATCH_ANY);
53}
54
55#elif defined(__FreeBSD__)
56#define UTIL_FUTEX_SUPPORTED 1
57
58#include <assert.h>
59#include <errno.h>
60#include <fcntl.h>
61#include <sys/types.h>
62#include <sys/umtx.h>
63#include <sys/time.h>
64
65static inline int futex_wake(uint32_t *addr, int count)
66{
67   assert(count == (int)(uint32_t)count); /* Check that bits weren't discarded */
68   return _umtx_op(addr, UMTX_OP_WAKE, (uint32_t)count, NULL, NULL) == -1 ? errno : 0;
69}
70
71static inline int futex_wait(uint32_t *addr, int32_t value, struct timespec *timeout)
72{
73   void *uaddr = NULL, *uaddr2 = NULL;
74   struct _umtx_time tmo = {
75      ._flags = UMTX_ABSTIME,
76      ._clockid = CLOCK_MONOTONIC
77   };
78
79   assert(value == (int)(uint32_t)value); /* Check that bits weren't discarded */
80
81   if (timeout != NULL) {
82      tmo._timeout = *timeout;
83      uaddr = (void *)(uintptr_t)sizeof(tmo);
84      uaddr2 = (void *)&tmo;
85   }
86
87   return _umtx_op(addr, UMTX_OP_WAIT_UINT, (uint32_t)value, uaddr, uaddr2) == -1 ? errno : 0;
88}
89
90#elif defined(__OpenBSD__)
91#define UTIL_FUTEX_SUPPORTED 1
92
93#include <sys/time.h>
94#include <sys/futex.h>
95
96static inline int futex_wake(uint32_t *addr, int count)
97{
98   return futex(addr, FUTEX_WAKE, count, NULL, NULL);
99}
100
101static inline int futex_wait(uint32_t *addr, int32_t value, const struct timespec *timeout)
102{
103   struct timespec tsnow, tsrel;
104
105   if (timeout == NULL)
106      return futex(addr, FUTEX_WAIT, value, NULL, NULL);
107
108   clock_gettime(CLOCK_MONOTONIC, &tsnow);
109   if (timespeccmp(&tsnow, timeout, <))
110      timespecsub(timeout, &tsnow, &tsrel);
111   else
112      timespecclear(&tsrel);
113   return futex(addr, FUTEX_WAIT, value, &tsrel, NULL);
114}
115
116#else
117#define UTIL_FUTEX_SUPPORTED 0
118#endif
119
120#endif /* UTIL_FUTEX_H */
121