Annotation of prex-old/sys/sync/cond.c, Revision 1.1.1.1
1.1 nbrk 1: /*-
2: * Copyright (c) 2005-2007, Kohsuke Ohtani
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: * 3. Neither the name of the author nor the names of any co-contributors
14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: */
29:
30: /*
31: * cond.c - condition variable object
32: */
33:
34: #include <kernel.h>
35: #include <sched.h>
36: #include <kmem.h>
37: #include <thread.h>
38: #include <sync.h>
39:
40: /*
41: * Create and initialize a condition variable (CV).
42: *
43: * If an initialized condition variable is reinitialized, undefined
44: * behavior results.
45: */
46: int
47: cond_init(cond_t *cond)
48: {
49: cond_t c;
50:
51: if ((c = kmem_alloc(sizeof(struct cond))) == NULL)
52: return ENOMEM;
53:
54: event_init(&c->event, "condition");
55: c->task = cur_task();
56: c->magic = COND_MAGIC;
57:
58: if (umem_copyout(&c, cond, sizeof(cond_t))) {
59: kmem_free(c);
60: return EFAULT;
61: }
62: return 0;
63: }
64:
65: /*
66: * cond_copyin - copy a condition variable from user space.
67: * @uc: pointer to cv in user space.
68: * @kc: pointer to cv in kernel space.
69: *
70: * It also checks if the passed CV is valid.
71: */
72: static int
73: cond_copyin(cond_t *ucond, cond_t *kcond)
74: {
75: cond_t c;
76:
77: if (umem_copyin(ucond, &c, sizeof(cond_t)))
78: return EFAULT;
79: if (!cond_valid(c))
80: return EINVAL;
81: *kcond = c;
82: return 0;
83: }
84:
85: /*
86: * Destroy a condition variable.
87: * If there are any blocked thread waiting for the specified CV,
88: * it returns EBUSY.
89: */
90: int
91: cond_destroy(cond_t *cond)
92: {
93: cond_t c;
94: int err;
95:
96: sched_lock();
97: if ((err = cond_copyin(cond, &c))) {
98: sched_unlock();
99: return err;
100: }
101: if (event_waiting(&c->event)) {
102: sched_unlock();
103: return EBUSY;
104: }
105: c->magic = 0;
106: kmem_free(c);
107: sched_unlock();
108: return 0;
109: }
110:
111: /*
112: * Wait on a condition.
113: *
114: * If the thread receives any exception while waiting CV, this
115: * routine returns immediately with EINTR in order to invoke
116: * exception handler. However, an application assumes this call
117: * does NOT return with an error. So, the stub routine in a system
118: * call library must call cond_wait() again if it gets EINTR as error.
119: */
120: int
121: cond_wait(cond_t *cond, mutex_t *mtx)
122: {
123: cond_t c;
124: int err, rc;
125:
126: if (umem_copyin(cond, &c, sizeof(cond_t)))
127: return EFAULT;
128:
129: sched_lock();
130: if (c == COND_INITIALIZER) {
131: if ((err = cond_init(cond))) {
132: sched_unlock();
133: return err;
134: }
135: umem_copyin(cond, &c, sizeof(cond_t));
136: } else {
137: if (!cond_valid(c)) {
138: sched_unlock();
139: return EINVAL;
140: }
141: }
142: if ((err = mutex_unlock(mtx))) {
143: sched_unlock();
144: return err;
145: }
146:
147: rc = sched_sleep(&c->event);
148: if (rc == SLP_INTR)
149: err = EINTR;
150: sched_unlock();
151:
152: if (err == 0)
153: err = mutex_lock(mtx);
154: return err;
155: }
156:
157: /*
158: * Unblock one thread that is blocked on the specified CV.
159: * The thread which has highest priority will be unblocked.
160: */
161: int
162: cond_signal(cond_t *cond)
163: {
164: cond_t c;
165: int err;
166:
167: sched_lock();
168: if ((err = cond_copyin(cond, &c)) == 0)
169: sched_wakeone(&c->event);
170: sched_unlock();
171: return err;
172: }
173:
174: /*
175: * Unblock all threads that are blocked on the specified CV.
176: */
177: int
178: cond_broadcast(cond_t *cond)
179: {
180: cond_t c;
181: int err;
182:
183: sched_lock();
184: if ((err = cond_copyin(cond, &c)) == 0)
185: sched_wakeup(&c->event);
186: sched_unlock();
187: return err;
188: }
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