root / prex-0.9.0 / usr / sample / mutex / mutex.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 | * mutex.c - sample program for mutex with priority inheritance.
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32 | */
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33 | |||
34 | /*
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35 | * Senario:
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36 | * This sample shows how the mutex priority is changed when three
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37 | * different threads lock two mutexes at same time.
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38 | *
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39 | * The priority of each thread are as follows.
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40 | * Thread1 - priority 100 (highest)
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41 | * Thread2 - priority 101
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42 | * Thread3 - priority 102
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43 | *
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44 | * Thread priority and state are changed as follows.
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45 | *
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46 | * Action Thread 1 Thread 2 Thread 3 Mutex A Mutex B
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47 | * ------------------------ -------- -------- -------- ------- -------
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48 | * 1) Thread 3 locks mutex A susp/100 susp/101 run /102 owner=3
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49 | * 2) Thread 2 locks mutex B susp/100 run /101 run /102 owner=3 owner=2
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50 | * 3) Thread 2 locks mutex A susp/100 wait/101 run /101* owner=3 owner=2
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51 | * 4) Thread 1 locks mutex B wait/100 wait/100* run /100* owner=3 owner=2
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52 | * 5) Thread 3 unlocks mutex A wait/100 run /100 run /102* owner=2* owner=2
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53 | * 6) Thread 2 unlocks mutex B run /100* run /100 run /102 owner=2 owner=1*
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54 | * 7) Thread 2 unlocks mutex A run /100 run /100 run /102 owner=1
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55 | * 8) Thread 1 unlocks mutex B wait/100 run /101 run /102
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56 | *
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57 | */
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58 | |||
59 | #include <sys/prex.h> |
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60 | #include <stdio.h> |
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61 | |||
62 | static char stack[3][1024]; |
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63 | static thread_t th_1, th_2, th_3;
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64 | static mutex_t mtx_A, mtx_B;
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65 | |||
66 | static void |
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67 | dump_pri(void)
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68 | { |
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69 | int pri;
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70 | |||
71 | if (thread_getpri(th_1, &pri) == 0) |
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72 | printf("th_1: pri=%d\n", pri);
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73 | |||
74 | if (thread_getpri(th_2, &pri) == 0) |
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75 | printf("th_2: pri=%d\n", pri);
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76 | |||
77 | if (thread_getpri(th_3, &pri) == 0) |
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78 | printf("th_3: pri=%d\n", pri);
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79 | } |
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80 | |||
81 | thread_t |
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82 | thread_run(void (*start)(void), void *stack) |
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83 | { |
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84 | thread_t t; |
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85 | |||
86 | if (thread_create(task_self(), &t) != 0) |
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87 | panic("thread_create is failed");
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88 | |||
89 | if (thread_load(t, start, stack) != 0) |
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90 | panic("thread_load is failed");
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91 | |||
92 | return t;
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93 | } |
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94 | |||
95 | /*
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96 | * Thread 1 - Priority = 100
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97 | */
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98 | static void |
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99 | thread_1(void)
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100 | { |
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101 | printf("thread_1: starting\n");
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102 | |||
103 | /*
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104 | * 4) Lock mutex B
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105 | *
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106 | * Priority inheritance:
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107 | * Thread 2... Pri 101 -> 100
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108 | * Thread 3... Pri 101 -> 100
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109 | */
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110 | printf("thread_1: 4) lock B\n");
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111 | mutex_lock(&mtx_B); |
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112 | |||
113 | printf("thread_1: running\n");
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114 | dump_pri(); |
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115 | |||
116 | /*
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117 | * 8) Unlock mutex B
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118 | */
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119 | printf("thread_1: 7) unlock B\n");
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120 | mutex_unlock(&mtx_B); |
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121 | |||
122 | dump_pri(); |
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123 | printf("thread_1: exit\n");
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124 | thread_terminate(th_1); |
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125 | } |
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126 | |||
127 | /*
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128 | * Thread 2 - Priority = 101
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129 | */
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130 | static void |
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131 | thread_2(void)
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132 | { |
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133 | printf("thread_2: starting\n");
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134 | |||
135 | /*
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136 | * 2) Lock mutex B
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137 | */
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138 | printf("thread_2: 2) lock B\n");
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139 | mutex_lock(&mtx_B); |
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140 | dump_pri(); |
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141 | |||
142 | /*
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143 | * 3) Lock mutex A (Switch to thread 3)
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144 | *
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145 | * Priority inheritance:
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146 | * Thread 3... Pri 102 -> 101
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147 | */
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148 | printf("thread_2: 3) lock A\n");
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149 | mutex_lock(&mtx_A); |
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150 | |||
151 | printf("thread_2: running\n");
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152 | dump_pri(); |
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153 | |||
154 | /*
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155 | * 6) Unlock mutex B
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156 | */
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157 | printf("thread_2: 6) unlock B\n");
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158 | mutex_unlock(&mtx_B); |
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159 | |||
160 | dump_pri(); |
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161 | |||
162 | /*
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163 | * 7) Unlock mutex A
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164 | */
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165 | printf("thread_2: 8) unlock A\n");
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166 | mutex_unlock(&mtx_A); |
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167 | |||
168 | printf("thread_2: exit\n");
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169 | thread_terminate(th_2); |
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170 | } |
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171 | |||
172 | |||
173 | /*
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174 | * Thread 3 - Priority = 102
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175 | */
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176 | static void |
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177 | thread_3(void)
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178 | { |
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179 | printf("thread_3: start\n");
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180 | |||
181 | /*
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182 | * 1) Lock mutex A
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183 | */
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184 | printf("thread_3: 1) lock A\n");
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185 | mutex_lock(&mtx_A); |
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186 | dump_pri(); |
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187 | |||
188 | /*
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189 | * Start thread 2
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190 | */
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191 | thread_resume(th_2); |
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192 | |||
193 | /*
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194 | * Check priority
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195 | */
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196 | printf("thread_3: running-1\n");
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197 | dump_pri(); |
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198 | |||
199 | /*
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200 | * Start thread 1
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201 | */
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202 | thread_resume(th_1); |
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203 | printf("thread_3: running-2\n");
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204 | dump_pri(); |
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205 | |||
206 | /*
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207 | * 5) Unlock mutex A
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208 | */
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209 | printf("thread_3: 5) unlock A\n");
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210 | mutex_unlock(&mtx_A); |
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211 | |||
212 | dump_pri(); |
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213 | printf("thread_3: exit\n");
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214 | thread_terminate(th_3); |
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215 | } |
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216 | |||
217 | int
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218 | main(int argc, char *argv[]) |
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219 | { |
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220 | printf("Mutex sample program\n");
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221 | |||
222 | /*
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223 | * Boost priority of this thread
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224 | */
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225 | thread_setpri(thread_self(), 90);
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226 | |||
227 | /*
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228 | * Initialize mutexes.
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229 | */
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230 | mutex_init(&mtx_A); |
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231 | mutex_init(&mtx_B); |
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232 | |||
233 | /*
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234 | * Create new threads
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235 | */
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236 | th_1 = thread_run(thread_1, stack[0]+1024); |
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237 | thread_setpri(th_1, 100);
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238 | |||
239 | th_2 = thread_run(thread_2, stack[1]+1024); |
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240 | thread_setpri(th_2, 101);
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241 | |||
242 | th_3 = thread_run(thread_3, stack[2]+1024); |
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243 | thread_setpri(th_3, 102);
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244 | |||
245 | dump_pri(); |
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246 | |||
247 | /*
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248 | * Start lowest priority thread
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249 | */
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250 | thread_resume(th_3); |
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251 | |||
252 | /*
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253 | * Wait...
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254 | */
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255 | thread_suspend(thread_self()); |
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256 | |||
257 | return 0; |
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258 | } |