root / prex-0.9.0 / usr / test / deadlock / deadlock.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*-
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2 | * Copyright (c) 2005, Kohsuke Ohtani
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the author nor the names of any co-contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | /*
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31 | * deadlock.c - test program for a kernel deadlock detection.
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32 | */
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33 | |||
34 | /*
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35 | * Prex kernel has the feature of deadlock detection. The following
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36 | * senario is tested with this program.
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37 | *
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38 | * 1) Thread-2 locks mutex-A.
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39 | * 2) Thread-1 locks mutex-B.
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40 | * 3) Thread-1 locks mutex-A.
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41 | * 4) Thread-2 locks mutex-B.
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42 | *
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43 | * The deadlock occurs at 4) because mutex-B has been already locked by
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44 | * thread-1 and thread-1 is waiting for thread-2 (mutex-A).
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45 | * The kernel will detect this condition, and the mutex_lock() system
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46 | * call will return EDEADLK error code.
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47 | */
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48 | |||
49 | #include <sys/prex.h> |
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50 | #include <stdio.h> |
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51 | #include <errno.h> |
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52 | |||
53 | static char stack[2][1024]; |
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54 | static thread_t th_1, th_2;
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55 | static mutex_t mtx_A, mtx_B;
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56 | |||
57 | thread_t |
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58 | thread_run(void (*start)(void), void *stack) |
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59 | { |
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60 | thread_t t; |
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61 | int error;
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62 | |||
63 | error = thread_create(task_self(), &t); |
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64 | if (error)
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65 | panic("thread_create is failed");
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66 | |||
67 | error = thread_load(t, start, stack); |
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68 | if (error)
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69 | panic("thread_load is failed");
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70 | |||
71 | return t;
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72 | } |
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73 | |||
74 | /*
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75 | * Thread 1 - Priority = 100
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76 | */
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77 | static void |
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78 | thread_1(void)
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79 | { |
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80 | int error;
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81 | |||
82 | printf("thread_1: starting\n");
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83 | |||
84 | /*
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85 | * 2) Lock mutex B
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86 | */
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87 | printf("thread_1: 2) lock B\n");
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88 | error = mutex_lock(&mtx_B); |
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89 | if (error) printf("error=%d\n", error); |
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90 | |||
91 | /*
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92 | * 3) Lock mutex A
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93 | *
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94 | * Switch to thread 1.
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95 | */
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96 | printf("thread_1: 3) lock A\n");
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97 | error = mutex_lock(&mtx_A); |
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98 | if (error) printf("error=%d\n", error); |
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99 | |||
100 | printf("thread_1: exit\n");
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101 | thread_terminate(th_1); |
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102 | } |
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103 | |||
104 | /*
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105 | * Thread 2 - Priority = 101
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106 | */
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107 | static void |
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108 | thread_2(void)
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109 | { |
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110 | int error;
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111 | |||
112 | printf("thread_2: starting\n");
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113 | |||
114 | /*
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115 | * 1) Lock mutex A
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116 | */
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117 | printf("thread_2: 1) lock A\n");
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118 | error = mutex_lock(&mtx_A); |
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119 | if (error) printf("error=%d\n", error); |
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120 | |||
121 | /*
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122 | * Switch to thread 1
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123 | */
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124 | thread_resume(th_1); |
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125 | |||
126 | printf("thread_2: running\n");
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127 | /*
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128 | * 4) Lock mutex B
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129 | *
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130 | * Deadlock occurs here!
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131 | */
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132 | printf("thread_2: 4) lock B\n");
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133 | error = mutex_lock(&mtx_B); |
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134 | if (error) printf("error=%d\n", error); |
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135 | if (error == EDEADLK)
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136 | printf("**** DEADLOCK!! ****\n");
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137 | |||
138 | printf("thread_2: exit\n");
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139 | thread_terminate(th_2); |
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140 | } |
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141 | |||
142 | int
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143 | main(int argc, char *argv[]) |
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144 | { |
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145 | printf("Deadlock test program\n");
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146 | |||
147 | /*
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148 | * Boost priority of this thread
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149 | */
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150 | thread_setpri(thread_self(), 90);
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151 | |||
152 | /*
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153 | * Initialize mutexes.
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154 | */
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155 | mutex_init(&mtx_A); |
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156 | mutex_init(&mtx_B); |
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157 | |||
158 | /*
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159 | * Create new threads
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160 | */
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161 | th_1 = thread_run(thread_1, stack[0]+1024); |
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162 | thread_setpri(th_1, 100);
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163 | |||
164 | th_2 = thread_run(thread_2, stack[1]+1024); |
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165 | thread_setpri(th_2, 101);
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166 | |||
167 | /*
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168 | * Start thread 2
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169 | */
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170 | thread_resume(th_2); |
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171 | |||
172 | /*
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173 | * Wait...
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174 | */
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175 | thread_suspend(thread_self()); |
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176 | |||
177 | return 0; |
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178 | } |