Annotation of prex-old/usr/test/deadlock/deadlock.c, Revision 1.1.1.1
1.1 nbrk 1: /*-
2: * Copyright (c) 2005, 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: * deadlock.c - test program for a kernel deadlock detection.
32: */
33:
34: /*
35: * Prex kernel has the feature of deadlock detection. The following
36: * senario is tested with this program.
37: *
38: * 1) Thread-2 locks mutex-A.
39: * 2) Thread-1 locks mutex-B.
40: * 3) Thread-1 locks mutex-A.
41: * 4) Thread-2 locks mutex-B.
42: *
43: * The deadlock occurs at 4) because mutex-B has been already locked by
44: * thread-1 and thread-1 is waiting for thread-2 (mutex-A).
45: * The kernel will detect this condition, and the mutex_lock() system
46: * call will return EDEADLK error code.
47: */
48:
49: #include <prex/prex.h>
50: #include <stdio.h>
51: #include <errno.h>
52:
53: static char stack[2][1024];
54: static thread_t th_1, th_2;
55: static mutex_t mtx_A, mtx_B;
56:
57: thread_t
58: thread_run(void (*start)(void), void *stack)
59: {
60: thread_t th;
61: int err;
62:
63: err = thread_create(task_self(), &th);
64: if (err)
65: panic("thread_create is failed");
66:
67: err = thread_load(th, start, stack);
68: if (err)
69: panic("thread_load is failed");
70:
71: return th;
72: }
73:
74: /*
75: * Thread 1 - Priority = 100
76: */
77: static void
78: thread_1(void)
79: {
80: int err;
81:
82: printf("thread_1: starting\n");
83:
84: /*
85: * 2) Lock mutex B
86: */
87: printf("thread_1: 2) lock B\n");
88: err = mutex_lock(&mtx_B);
89: if (err) printf("err=%d\n", err);
90:
91: /*
92: * 3) Lock mutex A
93: *
94: * Switch to thread 1.
95: */
96: printf("thread_1: 3) lock A\n");
97: err = mutex_lock(&mtx_A);
98: if (err) printf("err=%d\n", err);
99:
100: printf("thread_1: exit\n");
101: thread_terminate(th_1);
102: }
103:
104: /*
105: * Thread 2 - Priority = 101
106: */
107: static void
108: thread_2(void)
109: {
110: int err;
111:
112: printf("thread_2: starting\n");
113:
114: /*
115: * 1) Lock mutex A
116: */
117: printf("thread_2: 1) lock A\n");
118: err = mutex_lock(&mtx_A);
119: if (err) printf("err=%d\n", err);
120:
121: /*
122: * Switch to thread 1
123: */
124: thread_resume(th_1);
125:
126: printf("thread_2: running\n");
127: /*
128: * 4) Lock mutex B
129: *
130: * Deadlock occurs here!
131: */
132: printf("thread_2: 4) lock B\n");
133: err = mutex_lock(&mtx_B);
134: if (err) printf("err=%d\n", err);
135: if (err == EDEADLK)
136: printf("**** DEADLOCK!! ****\n");
137:
138: printf("thread_2: exit\n");
139: thread_terminate(th_2);
140: }
141:
142: int
143: main(int argc, char *argv[])
144: {
145: printf("Deadlock test program\n");
146:
147: /*
148: * Boost priority of this thread
149: */
150: thread_setprio(thread_self(), 90);
151:
152: /*
153: * Initialize mutexes.
154: */
155: mutex_init(&mtx_A);
156: mutex_init(&mtx_B);
157:
158: /*
159: * Create new threads
160: */
161: th_1 = thread_run(thread_1, stack[0]+1024);
162: thread_setprio(th_1, 100);
163:
164: th_2 = thread_run(thread_2, stack[1]+1024);
165: thread_setprio(th_2, 101);
166:
167: /*
168: * Start thread 2
169: */
170: thread_resume(th_2);
171:
172: /*
173: * Wait...
174: */
175: thread_suspend(thread_self());
176:
177: return 0;
178: }
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