1 /*-
2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
3  * Copyright (c) 2005 Matthew Dillon <dillon@backplane.com>
4  *
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * $DragonFly: src/lib/libthread_xu/thread/thr_umtx.c,v 1.3 2006/04/04 14:04:39 davidxu Exp $
29  */
30 
31 #include <assert.h>
32 #include <errno.h>
33 #include <unistd.h>
34 #include <sys/time.h>
35 
36 #include "thr_private.h"
37 
38 /*
39  * This function is used to acquire a contested lock.
40  */
41 int
42 __thr_umtx_lock(volatile umtx_t *mtx, int timo)
43 {
44 	int v, ret = 0;
45 
46 	/* contested */
47 	do {
48 		v = *mtx;
49 		if (v == 2 || atomic_cmpset_acq_int(mtx, 1, 2)) {
50 			if (timo == 0)
51 				umtx_sleep(mtx, 2, timo);
52 			else if (umtx_sleep(mtx, 2, timo) < 0) {
53 				if (errno == EAGAIN) {
54 					if (atomic_cmpset_acq_int(mtx, 0, 2))
55 						ret = 0;
56 					else
57 						ret = ETIMEDOUT;
58 					break;
59 				}
60 			}
61 		}
62 	} while (!atomic_cmpset_acq_int(mtx, 0, 2));
63 
64 	return (ret);
65 }
66 
67 void
68 __thr_umtx_unlock(volatile umtx_t *mtx)
69 {
70 	int v;
71 
72 	for (;;) {
73 		v = *mtx;
74 		if (atomic_cmpset_acq_int(mtx, v, v-1)) {
75 			if (v != 1) {
76 				*mtx = 0;
77 				umtx_wakeup(mtx, 1);
78 			}
79 			break;
80 		}
81 	}
82 }
83 
84 int
85 __thr_umtx_timedlock(volatile umtx_t *mtx, const struct timespec *timeout)
86 {
87     struct timespec ts, ts2, ts3;
88     int timo, ret;
89 
90     if ((timeout->tv_sec < 0) ||
91         (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
92 	return (ETIMEDOUT);
93 
94     /* XXX there should have MONO timer! */
95     clock_gettime(CLOCK_REALTIME, &ts);
96     TIMESPEC_ADD(&ts, &ts, timeout);
97     ts2 = *timeout;
98 
99     for (;;) {
100     	if (ts2.tv_nsec) {
101 	    timo = (int)(ts2.tv_nsec / 1000);
102 	    if (timo == 0)
103 		timo = 1;
104 	} else {
105 	    timo = 1000000;
106 	}
107 	ret = __thr_umtx_lock(mtx, timo);
108 	if (ret != ETIMEDOUT)
109 	    break;
110 	clock_gettime(CLOCK_REALTIME, &ts3);
111 	TIMESPEC_SUB(&ts2, &ts, &ts3);
112 	if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
113 	    ret = ETIMEDOUT;
114 	    break;
115 	}
116     }
117     return (ret);
118 }
119 
120 int
121 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout,
122 	int clockid)
123 {
124     struct timespec ts, ts2, ts3;
125     int timo, ret = 0;
126 
127     if (*mtx != exp)
128 	return (0);
129 
130     if (timeout == NULL) {
131 	if (umtx_sleep(mtx, exp, 0) < 0) {
132 	    if (errno == EINTR)
133 		ret = EINTR;
134 	}
135 	return (ret);
136     }
137 
138     if ((timeout->tv_sec < 0) ||
139         (timeout->tv_sec == 0 && timeout->tv_nsec <= 0))
140 	return (ETIMEDOUT);
141 
142     clock_gettime(clockid, &ts);
143     TIMESPEC_ADD(&ts, &ts, timeout);
144     ts2 = *timeout;
145 
146     for (;;) {
147     	if (ts2.tv_nsec) {
148 	    timo = (int)(ts2.tv_nsec / 1000);
149 	    if (timo == 0)
150 		timo = 1;
151 	} else {
152 	    timo = 1000000;
153 	}
154 	if (umtx_sleep(mtx, exp, timo) < 0) {
155 	    if (errno == EBUSY) {
156 		ret = 0;
157 		break;
158 	    } else if (errno == EINTR) {
159 		ret = EINTR;
160 		break;
161 	    }
162 	}
163 	clock_gettime(clockid, &ts3);
164 	TIMESPEC_SUB(&ts2, &ts, &ts3);
165 	if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) {
166 	    ret = ETIMEDOUT;
167 	    break;
168 	}
169     }
170     return (ret);
171 }
172 
173 void _thr_umtx_wake(volatile umtx_t *mtx, int count)
174 {
175     umtx_wakeup(mtx, count);
176 }
177