root / prex-0.9.0 / usr / server / proc / proc_fork.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*
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2 | * Copyright (c) 2005-2006, 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 | * fork.c - fork() support
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32 | */
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33 | |||
34 | #include <sys/prex.h> |
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35 | #include <ipc/proc.h> |
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36 | #include <sys/list.h> |
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37 | |||
38 | #include <unistd.h> |
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39 | #include <errno.h> |
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40 | #include <stdlib.h> |
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41 | #include <string.h> |
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42 | |||
43 | #include "proc.h" |
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44 | |||
45 | static int vfork_start(struct proc *); |
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46 | |||
47 | /*
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48 | * PID previously allocated.
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49 | *
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50 | * Note: The following pids are reserved by default.
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51 | * pid = 0: Process server
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52 | * pid = 1: Init process
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53 | */
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54 | static pid_t last_pid = 1; |
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55 | |||
56 | /*
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57 | * Assign new pid.
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58 | * Returns pid on sucess, or 0 on failure.
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59 | */
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60 | static pid_t
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61 | pid_alloc(void)
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62 | { |
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63 | pid_t pid; |
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64 | |||
65 | pid = last_pid + 1;
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66 | if (pid >= PID_MAX)
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67 | pid = 1;
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68 | while (pid != last_pid) {
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69 | if (p_find(pid) == NULL) |
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70 | break;
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71 | if (++pid >= PID_MAX)
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72 | pid = 1;
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73 | } |
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74 | if (pid == last_pid)
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75 | return 0; |
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76 | last_pid = pid; |
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77 | return pid;
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78 | } |
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79 | |||
80 | /*
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81 | * Create a new process.
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82 | */
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83 | int
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84 | newproc(struct proc *p, pid_t pid, task_t task)
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85 | { |
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86 | struct pgrp *pg;
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87 | |||
88 | pg = curproc->p_pgrp; |
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89 | |||
90 | if (pid == 0) { |
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91 | pid = pid_alloc(); |
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92 | if (pid == 0) { |
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93 | /* Too many processes */
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94 | return EAGAIN;
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95 | } |
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96 | } |
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97 | /*
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98 | * make proc entry for new proc
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99 | */
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100 | p->p_parent = curproc; |
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101 | p->p_pgrp = pg; |
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102 | p->p_stat = SRUN; |
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103 | p->p_exitcode = 0;
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104 | p->p_pid = pid; |
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105 | p->p_task = task; |
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106 | p->p_vforked = 0;
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107 | p->p_invfork = 0;
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108 | |||
109 | list_init(&p->p_children); |
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110 | p_add(p); |
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111 | list_insert(&curproc->p_children, &p->p_sibling); |
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112 | list_insert(&pg->pg_members, &p->p_pgrp_link); |
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113 | list_insert(&allproc, &p->p_link); |
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114 | |||
115 | return 0; |
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116 | } |
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117 | |||
118 | /*
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119 | * fork() support.
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120 | *
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121 | * It creates new process data and update all process relations.
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122 | * The task creation and the thread creation are done by the
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123 | * fork() library stub.
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124 | */
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125 | int
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126 | sys_fork(task_t child, int vfork, pid_t *retval)
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127 | { |
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128 | struct proc *p;
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129 | int error;
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130 | |||
131 | DPRINTF(("proc: fork child=%x vfork=%d\n", child, vfork));
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132 | |||
133 | if (vfork && curproc->p_invfork) {
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134 | DPRINTF(("proc: vfork under vfork!\n"));
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135 | return EINVAL;
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136 | } |
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137 | |||
138 | if (task_to_proc(child) != NULL) { |
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139 | DPRINTF(("proc: process already exists\n"));
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140 | return EINVAL;
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141 | } |
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142 | |||
143 | if ((p = malloc(sizeof(struct proc))) == NULL) |
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144 | return ENOMEM;
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145 | memset(p, 0, sizeof(*p)); |
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146 | |||
147 | error = newproc(p, 0, child);
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148 | if (error)
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149 | return error;
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150 | |||
151 | if (vfork) {
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152 | vfork_start(curproc); |
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153 | p->p_invfork = 1;
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154 | } |
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155 | |||
156 | DPRINTF(("proc: fork newpid=%d\n", p->p_pid));
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157 | *retval = p->p_pid; |
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158 | return 0; |
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159 | } |
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160 | |||
161 | /*
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162 | * Clean up all resource created by fork().
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163 | */
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164 | void
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165 | cleanup(struct proc *p)
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166 | { |
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167 | struct proc *pp;
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168 | |||
169 | DPRINTF(("proc: cleanup pid=%d\n", p->p_pid));
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170 | pp = p->p_parent; |
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171 | list_remove(&p->p_sibling); |
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172 | list_remove(&p->p_pgrp_link); |
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173 | list_remove(&p->p_link); |
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174 | free(p); |
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175 | } |
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176 | |||
177 | static int |
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178 | vfork_start(struct proc *p)
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179 | { |
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180 | void *stack;
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181 | |||
182 | /*
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183 | * Save parent's stack
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184 | */
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185 | DPRINTF(("proc: vfork_start stack=%x\n", p->p_stackbase));
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186 | |||
187 | if (vm_allocate(p->p_task, &stack, DFLSTKSZ, 1) != 0) { |
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188 | DPRINTF(("proc: failed to allocate save stack\n"));
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189 | return ENOMEM;
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190 | } |
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191 | |||
192 | memcpy(stack, p->p_stackbase, DFLSTKSZ); |
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193 | p->p_stacksaved = stack; |
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194 | |||
195 | p->p_vforked = 1;
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196 | return 0; |
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197 | } |
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198 | |||
199 | void
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200 | vfork_end(struct proc *p)
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201 | { |
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202 | |||
203 | DPRINTF(("proc: vfork_end org=%x saved=%x\n", p->p_stackbase,
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204 | p->p_stacksaved)); |
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205 | /*
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206 | * Restore parent's stack
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207 | */
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208 | memcpy(p->p_stackbase, p->p_stacksaved, DFLSTKSZ); |
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209 | vm_free(p->p_task, p->p_stacksaved); |
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210 | |||
211 | /*
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212 | * Resume parent
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213 | */
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214 | p->p_vforked = 0;
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215 | task_resume(p->p_task); |
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216 | } |