1 /* $OpenBSD: synch.h,v 1.7 2021/06/13 21:11:54 kettenis Exp $ */ 2 /* 3 * Copyright (c) 2017 Martin Pieuchot 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/atomic.h> 19 #include <sys/time.h> 20 #include <sys/futex.h> 21 22 static inline int 23 _wake(volatile uint32_t *p, int n) 24 { 25 return futex(p, FUTEX_WAKE_PRIVATE, n, NULL, NULL); 26 } 27 28 static inline int 29 _twait(volatile uint32_t *p, int val, clockid_t clockid, const struct timespec *abs) 30 { 31 struct timespec rel; 32 int saved_errno = errno; 33 int error; 34 35 if (abs == NULL) { 36 error = futex(p, FUTEX_WAIT_PRIVATE, val, NULL, NULL); 37 if (error == -1) { 38 error = errno; 39 errno = saved_errno; 40 } 41 return error; 42 } 43 44 if (abs->tv_nsec >= 1000000000 || WRAP(clock_gettime)(clockid, &rel)) 45 return EINVAL; 46 47 rel.tv_sec = abs->tv_sec - rel.tv_sec; 48 if ((rel.tv_nsec = abs->tv_nsec - rel.tv_nsec) < 0) { 49 rel.tv_sec--; 50 rel.tv_nsec += 1000000000; 51 } 52 if (rel.tv_sec < 0) 53 return ETIMEDOUT; 54 55 error = futex(p, FUTEX_WAIT_PRIVATE, val, &rel, NULL); 56 if (error == -1) { 57 error = errno; 58 errno = saved_errno; 59 } 60 return error; 61 } 62 63 static inline int 64 _requeue(volatile uint32_t *p, int n, int m, volatile uint32_t *q) 65 { 66 return futex(p, FUTEX_REQUEUE_PRIVATE, n, (void *)(long)m, q); 67 } 68