1 /*-
2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  */
27 
28 #ifndef _THR_DFLY_UMTX_H_
29 #define _THR_DFLY_UMTX_H_
30 
31 #include <unistd.h>
32 
33 #define	cpu_pause()	__asm __volatile("pause":::"memory")
34 
35 typedef int umtx_t;
36 
37 int	__thr_umtx_lock(volatile umtx_t *mtx, int id, int timo);
38 int	__thr_umtx_timedlock(volatile umtx_t *mtx, int id,
39 		 const struct timespec *timeout);
40 void	__thr_umtx_unlock(volatile umtx_t *mtx, int v, int id);
41 
42 static inline void
43 _thr_umtx_init(volatile umtx_t *mtx)
44 {
45 	*mtx = 0;
46 }
47 
48 static inline int
49 _thr_umtx_trylock(volatile umtx_t *mtx, int id, int temporary)
50 {
51 	if (temporary)
52 		sigblockall();
53 	if (atomic_cmpset_acq_int(mtx, 0, id))
54 		return (0);
55 	cpu_pause();
56 	if (atomic_cmpset_acq_int(mtx, 0, id))
57 		return (0);
58 	cpu_pause();
59 	if (atomic_cmpset_acq_int(mtx, 0, id))
60 		return (0);
61 	if (temporary)
62 		sigunblockall();
63 	return (EBUSY);
64 }
65 
66 static inline int
67 _thr_umtx_lock(volatile umtx_t *mtx, int id, int temporary)
68 {
69 	int res;
70 
71 	if (temporary)
72 		sigblockall();
73 	if (atomic_cmpset_acq_int(mtx, 0, id))
74 		return (0);
75 	res = __thr_umtx_lock(mtx, id, 0);
76 	if (res && temporary)
77 		sigunblockall();
78 	return res;
79 }
80 
81 static inline int
82 _thr_umtx_timedlock(volatile umtx_t *mtx, int id,
83     const struct timespec *timeout, int temporary)
84 {
85 	int res;
86 
87 	if (temporary)
88 		sigblockall();
89 	if (atomic_cmpset_acq_int(mtx, 0, id)) {
90 		return (0);
91 	}
92 	res = __thr_umtx_timedlock(mtx, id, timeout);
93 	if (res && temporary)
94 		sigunblockall();
95 	return res;
96 }
97 
98 static inline void
99 _thr_umtx_unlock(volatile umtx_t *mtx, int id, int temporary)
100 {
101 	int v;
102 
103 	v = atomic_swap_int(mtx, 0);
104 	if (v != id)
105 		__thr_umtx_unlock(mtx, v, id);
106 	if (temporary)
107 		sigunblockall();
108 }
109 
110 int _thr_umtx_wait(volatile umtx_t *mtx, umtx_t exp,
111 		   const struct timespec *timeout, int clockid);
112 int _thr_umtx_wait_intr(volatile umtx_t *mtx, umtx_t exp);
113 void _thr_umtx_wake(volatile umtx_t *mtx, int count);
114 #endif
115