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2 | pj | 1 | /* |
2 | * Project: S.Ha.R.K. |
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3 | * |
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4 | * Coordinators: |
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5 | * Giorgio Buttazzo <giorgio@sssup.it> |
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6 | * Paolo Gai <pj@gandalf.sssup.it> |
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7 | * |
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8 | * Authors : |
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9 | * Paolo Gai <pj@gandalf.sssup.it> |
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10 | * Massimiliano Giorgi <massy@gandalf.sssup.it> |
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11 | * Luca Abeni <luca@gandalf.sssup.it> |
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12 | * (see the web pages for full authors list) |
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13 | * |
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14 | * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy) |
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15 | * |
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16 | * http://www.sssup.it |
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17 | * http://retis.sssup.it |
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18 | * http://shark.sssup.it |
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19 | */ |
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20 | |||
21 | /** |
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22 | ------------ |
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320 | giacomo | 23 | CVS : $Id: conditio.c,v 1.5 2003-11-06 08:55:53 giacomo Exp $ |
2 | pj | 24 | |
25 | File: $File$ |
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320 | giacomo | 26 | Revision: $Revision: 1.5 $ |
27 | Last update: $Date: 2003-11-06 08:55:53 $ |
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2 | pj | 28 | ------------ |
29 | |||
30 | This file contains the condition variables handling functions. |
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31 | |||
32 | **/ |
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33 | |||
34 | /* |
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35 | * Copyright (C) 2000 Paolo Gai |
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36 | * |
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37 | * This program is free software; you can redistribute it and/or modify |
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38 | * it under the terms of the GNU General Public License as published by |
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39 | * the Free Software Foundation; either version 2 of the License, or |
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40 | * (at your option) any later version. |
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41 | * |
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42 | * This program is distributed in the hope that it will be useful, |
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43 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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44 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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45 | * GNU General Public License for more details. |
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46 | * |
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47 | * You should have received a copy of the GNU General Public License |
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48 | * along with this program; if not, write to the Free Software |
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49 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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50 | * |
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51 | */ |
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52 | |||
53 | |||
54 | |||
55 | #include <kernel/const.h> |
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56 | #include <sys/types.h> |
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57 | #include <kernel/model.h> |
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58 | #include <kernel/descr.h> |
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59 | #include <kernel/var.h> |
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60 | #include <kernel/func.h> |
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61 | #include <errno.h> |
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29 | pj | 62 | #include <kernel/iqueue.h> |
2 | pj | 63 | |
64 | /*---------------------------------------------------------------------*/ |
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65 | /* Condition variables */ |
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66 | /*---------------------------------------------------------------------*/ |
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67 | |||
68 | static int condition_once = 1; |
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69 | |||
70 | /* this is the test that is done when a task is being killed |
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71 | and it is waiting on a condition */ |
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72 | static int condition_cancellation_point(PID i, void *arg) |
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73 | { |
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74 | LEVEL l; |
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75 | |||
76 | if (proc_table[i].status == WAIT_COND) { |
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77 | /* if the task is waiting on a condition variable, we have to extract it |
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78 | from the waiters queue, then set the KILL_REQUEST flag, and reinsert |
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79 | the task into the ready queue so it can reaquire the mutex and die */ |
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29 | pj | 80 | iq_extract(i,&proc_table[i].cond_waiting->waiters); |
81 | if (iq_isempty(&proc_table[i].cond_waiting->waiters)) |
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2 | pj | 82 | proc_table[i].cond_waiting->used_for_waiting = NULL; |
83 | proc_table[i].cond_waiting = NULL; |
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84 | |||
85 | l = proc_table[i].task_level; |
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38 | pj | 86 | level_table[l]->public_unblock(l,i); |
2 | pj | 87 | /* then, the kill_request flag is set, and when the task is rescheduled |
88 | it autokill itself... */ |
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89 | |||
90 | return 1; |
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91 | } |
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92 | |||
93 | return 0; |
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94 | } |
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95 | |||
96 | |||
97 | int cond_init(cond_t *cond) |
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98 | { |
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99 | /* first, if it is the first time that the cond_init is called, |
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100 | register the cancellation point */ |
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101 | if (condition_once) { |
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102 | condition_once = 0; |
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103 | register_cancellation_point(condition_cancellation_point, NULL); |
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104 | } |
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105 | |||
29 | pj | 106 | iq_init (&cond->waiters, &freedesc, 0); |
107 | |||
2 | pj | 108 | cond->used_for_waiting = NULL; |
109 | |||
110 | return 0; |
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111 | } |
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112 | |||
113 | int cond_destroy(cond_t *cond) |
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114 | { |
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29 | pj | 115 | if (!iq_isempty(&cond->waiters)) |
2 | pj | 116 | return (EBUSY); |
117 | |||
118 | return 0; |
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119 | } |
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120 | |||
121 | int cond_signal(cond_t *cond) |
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122 | { |
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123 | LEVEL l; |
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124 | PID p; |
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125 | |||
126 | proc_table[exec_shadow].context = kern_context_save(); |
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127 | |||
29 | pj | 128 | if (!iq_isempty(&cond->waiters)) { |
129 | p = iq_getfirst(&cond->waiters); |
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2 | pj | 130 | |
131 | l = proc_table[p].task_level; |
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38 | pj | 132 | level_table[l]->public_unblock(l,p); |
2 | pj | 133 | |
134 | scheduler(); |
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135 | } |
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136 | |||
137 | kern_context_load(proc_table[exec_shadow].context); |
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138 | return 0; |
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139 | } |
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140 | |||
141 | int cond_broadcast(cond_t *cond) |
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142 | { |
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143 | LEVEL l; |
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144 | PID p; |
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145 | |||
146 | proc_table[exec_shadow].context = kern_context_save(); |
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147 | |||
29 | pj | 148 | if (!iq_isempty(&cond->waiters)) { |
2 | pj | 149 | do { |
29 | pj | 150 | p = iq_getfirst(&cond->waiters); |
2 | pj | 151 | |
152 | l = proc_table[p].task_level; |
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38 | pj | 153 | level_table[l]->public_unblock(l,p); |
29 | pj | 154 | } while(!iq_isempty(&cond->waiters)); |
2 | pj | 155 | |
156 | scheduler(); |
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157 | } |
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158 | kern_context_load(proc_table[exec_shadow].context); |
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159 | return 0; |
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160 | } |
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161 | |||
162 | int cond_wait(cond_t *cond, mutex_t *mutex) |
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163 | { |
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164 | LEVEL l; |
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165 | |||
166 | /* Why I used task_nopreempt???... because we have to unlock the mutex, |
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167 | and we can't call mutex_unlock after kern_context_save (the unlock |
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168 | could call context_save itself...) */ |
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169 | task_nopreempt(); |
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170 | |||
171 | /* First, the cond_wait is a cancellation point... */ |
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172 | task_testcancel(); |
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173 | |||
174 | /* all the task that uses NOW this condition are waiting on the same |
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175 | mutex??? */ |
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176 | if (cond->used_for_waiting) { |
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177 | if (cond->used_for_waiting != mutex) { |
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178 | task_preempt(); |
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179 | return (EINVAL); |
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180 | } |
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181 | } |
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182 | else |
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183 | cond->used_for_waiting = mutex; |
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184 | |||
185 | /* If the task is not canceled with testcancel, we block it now... */ |
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186 | |||
187 | /* The mutex can't be destroyed while we are waiting on a condition, |
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188 | so we tell the mutex that a task is using it althought it is not |
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189 | busy (the cond_wait have to unlock the mutex!!!)... */ |
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190 | mutex->use++; |
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191 | if (mutex_unlock(mutex)) { |
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192 | /* some problems unlocking the mutex... */ |
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193 | mutex->use--; |
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194 | task_preempt(); |
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195 | return (EINVAL); |
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196 | } |
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197 | |||
198 | /* now, we really block the task... */ |
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199 | proc_table[exec_shadow].context = kern_context_save(); |
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200 | |||
38 | pj | 201 | kern_epilogue_macro(); |
2 | pj | 202 | |
203 | l = proc_table[exec_shadow].task_level; |
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38 | pj | 204 | level_table[l]->public_block(l,exec_shadow); |
2 | pj | 205 | |
206 | /* we insert the task in the condition queue */ |
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207 | proc_table[exec_shadow].status = WAIT_COND; |
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29 | pj | 208 | iq_priority_insert(exec_shadow,&cond->waiters); |
2 | pj | 209 | |
210 | /* then, we set into the processor descriptor the condition on that |
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211 | the task is blocked... (if the task is killed while it is waiting |
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212 | on the condition, we have to remove it from the waiters queue, so |
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213 | we need the condition variable...) */ |
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214 | proc_table[exec_shadow].cond_waiting = cond; |
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215 | |||
216 | /* and finally we reschedule */ |
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217 | exec = exec_shadow = -1; |
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218 | scheduler(); |
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219 | ll_context_to(proc_table[exec_shadow].context); |
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320 | giacomo | 220 | kern_sti(); |
2 | pj | 221 | |
222 | /* when we arrive here: |
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223 | - the task did't die while it was waiting on the condition |
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224 | (normally, the cancelability state is set to deferred; |
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225 | if someone kills the task, we have first to lock the mutex, |
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226 | and then die. Furthermore no cond_signal can be catched by a task |
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227 | that have to die, so in the makefree function we extract the |
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228 | task from the waiters queue) |
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229 | - the task still in the non-preemptive state |
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230 | - the task have to reaquire the mutex to test again the condition |
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231 | - the task have to reset the cond_waiting pointer set before |
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232 | */ |
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233 | if (proc_table[exec_shadow].cond_waiting != NULL) { |
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234 | proc_table[exec_shadow].cond_waiting = NULL; |
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235 | |||
29 | pj | 236 | if (iq_isempty(&cond->waiters)) cond->used_for_waiting = NULL; |
2 | pj | 237 | } |
238 | task_preempt(); |
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239 | |||
240 | mutex_lock(mutex); |
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241 | mutex->use--; |
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242 | |||
243 | task_testcancel(); |
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244 | |||
245 | return 0; |
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246 | } |
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247 | |||
248 | |||
249 | /* if this event fires the task passed as argument is blocked on a condition |
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250 | with a cond_timedwait. |
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251 | We have to: |
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252 | - extract the task from the waiters queue, because the task has to be |
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253 | woken up and must not use any cond_signal |
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254 | - reset the delaytimer... |
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255 | - call the task-insert... |
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256 | */ |
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257 | void condition_timer(void *arg) |
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258 | { |
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259 | PID p = (PID)arg; |
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260 | LEVEL l; |
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261 | |||
29 | pj | 262 | iq_extract(p,&proc_table[p].cond_waiting->waiters); |
263 | if (iq_isempty(&proc_table[p].cond_waiting->waiters)) |
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2 | pj | 264 | proc_table[p].cond_waiting->used_for_waiting = NULL; |
265 | proc_table[p].cond_waiting = NULL; |
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266 | |||
267 | proc_table[p].delay_timer = -1; |
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268 | |||
269 | l = proc_table[p].task_level; |
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38 | pj | 270 | level_table[l]->public_unblock(l,p); |
2 | pj | 271 | |
272 | event_need_reschedule(); |
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273 | } |
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274 | |||
275 | int cond_timedwait(cond_t *cond, mutex_t *mutex, |
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276 | const struct timespec *abstime) |
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277 | { |
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278 | LEVEL l; |
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279 | int returnvalue = 0; |
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280 | |||
281 | /* Why I used task_nopreempt???... because we have to unlock the mutex, |
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282 | and we can't call mutex_unlock after kern_context_save (the unlock |
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283 | could call context_save itself...) */ |
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284 | task_nopreempt(); |
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285 | |||
286 | /* First, the cond_wait is a cancellation point... */ |
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287 | task_testcancel(); |
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288 | |||
289 | /* all the task that uses NOW this condition are waiting on the same |
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290 | mutex??? */ |
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291 | if (cond->used_for_waiting) { |
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292 | if (cond->used_for_waiting != mutex) { |
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293 | task_preempt(); |
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294 | return (EINVAL); |
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295 | } |
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296 | } |
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297 | else |
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298 | cond->used_for_waiting = mutex; |
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299 | |||
300 | /* If the task is not canceled with testcancel, we block it now... */ |
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301 | |||
302 | /* The mutex can't be destroyed while we are waiting on a condition, |
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303 | so we tell the mutex that a task is using it althought it is not |
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304 | busy (the cond_wait have to unlock the mutex!!!)... */ |
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305 | mutex->use++; |
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306 | if (mutex_unlock(mutex)) { |
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307 | /* some problems unlocking the mutex... */ |
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308 | mutex->use--; |
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309 | task_preempt(); |
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310 | return (EINVAL); |
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311 | } |
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312 | |||
313 | /* now, we really block the task... */ |
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314 | proc_table[exec_shadow].context = kern_context_save(); |
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315 | |||
38 | pj | 316 | kern_epilogue_macro(); |
2 | pj | 317 | |
318 | l = proc_table[exec_shadow].task_level; |
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38 | pj | 319 | level_table[l]->public_block(l,exec_shadow); |
2 | pj | 320 | |
321 | /* we insert the task in the condition queue */ |
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322 | proc_table[exec_shadow].status = WAIT_COND; |
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29 | pj | 323 | iq_priority_insert(exec_shadow,&cond->waiters); |
2 | pj | 324 | |
325 | /* then, we set into the processor descriptor the condition on that |
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326 | the task is blocked... (if the task is killed while it is waiting |
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327 | on the condition, we have to remove it from the waiters queue, so |
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328 | we need the condition variable...) */ |
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329 | proc_table[exec_shadow].cond_waiting = cond; |
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330 | |||
331 | /* we can use the delaytimer because if we are here we are not in a |
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332 | task_delay */ |
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333 | proc_table[exec_shadow].delay_timer = |
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334 | kern_event_post(abstime,condition_timer,(void *)exec_shadow); |
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335 | |||
336 | /* and finally we reschedule */ |
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337 | exec = exec_shadow = -1; |
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338 | scheduler(); |
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339 | ll_context_to(proc_table[exec_shadow].context); |
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340 | |||
341 | if (proc_table[exec_shadow].delay_timer != -1) |
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38 | pj | 342 | kern_event_delete(proc_table[exec_shadow].delay_timer); |
2 | pj | 343 | |
320 | giacomo | 344 | kern_sti(); |
2 | pj | 345 | /* when we arrive here: |
346 | - the task did't die while it was waiting on the condition |
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347 | (normally, the cancelability state is set to deferred; |
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348 | if someone kills the task, we have first to lock the mutex, |
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349 | and then die. Furthermore no cond_signal can be catched by a task |
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350 | that have to die, so in the makefree function we extract the |
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351 | task from the waiters queue) |
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352 | - the task still in the non-preemptive state |
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353 | - the task have to reaquire the mutex to test again the condition |
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354 | - the task have to reset the cond_waiting pointer set before |
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355 | Note that cond_wait has to be called with cancelability set to |
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356 | deferred... so we insert a testcancel after the mutex_lock... |
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357 | */ |
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358 | if (proc_table[exec_shadow].cond_waiting != NULL) { |
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359 | proc_table[exec_shadow].cond_waiting = NULL; |
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360 | |||
29 | pj | 361 | if (iq_isempty(&cond->waiters)) cond->used_for_waiting = NULL; |
2 | pj | 362 | } |
363 | else |
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364 | /* cond_waiting == NULL if the task is killed or the timer has fired */ |
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365 | returnvalue = ETIMEDOUT; |
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366 | |||
367 | task_preempt(); |
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368 | |||
369 | mutex_lock(mutex); |
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370 | mutex->use--; |
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371 | |||
372 | task_testcancel(); |
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373 | |||
374 | return returnvalue; |
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375 | } |