scoutos / prex-0.9.0 / sys / ipc / object.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*-
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2 | * Copyright (c) 2005-2008, 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 | * object.c - object service
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32 | */
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33 | |||
34 | /**
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35 | * IPC object:
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36 | *
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37 | * An object represents service, state, or policies etc. To manipulate
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38 | * objects, kernel provide 3 functions: create, destroy and lookup.
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39 | * Prex task will create an object to provide its services to other
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40 | * tasks. The tasks will communicate by sending a message to the
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41 | * object each other. In typical case, a server task creates an object
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42 | * and client tasks will send a request message to it.
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43 | *
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44 | * A substance of object is stored in kernel space, and so it's protected
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45 | * from user mode code. Usually, an object has a unique name within a
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46 | * system. Before a task sends a message to the specific object, it must
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47 | * obtain the object ID by looking up the name of the target object.
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48 | *
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49 | * A task can create a private object which does not have name. Since
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50 | * another task can not obtain the ID of such object, the IPC operations
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51 | * for the private object are limited to the threads in the same task.
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52 | *
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53 | * The object name started with '!' means that it is a protected object.
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54 | * The protected object can be created only by the task which has
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55 | * CAP_PROTSERV capability. Since this capability is given to the known
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56 | * system servers, the client task can always trust the object owner.
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57 | */
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58 | |||
59 | #include <kernel.h> |
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60 | #include <kmem.h> |
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61 | #include <sched.h> |
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62 | #include <task.h> |
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63 | #include <ipc.h> |
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64 | |||
65 | /* forward declarations */
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66 | static object_t object_find(const char *); |
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67 | |||
68 | static struct list object_list; /* list of all objects */ |
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69 | |||
70 | /*
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71 | * Create a new object.
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72 | *
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73 | * The ID of the new object is stored in objp on success.
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74 | * The name of the object must be unique in the system.
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75 | * Or, the object can be created without name by setting
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76 | * NULL as name argument. This object can be used as a
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77 | * private object which can be accessed only by threads in
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78 | * same task.
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79 | */
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80 | int
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81 | object_create(const char *name, object_t *objp) |
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82 | { |
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83 | struct object *obj = 0; |
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84 | char str[MAXOBJNAME];
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85 | int error;
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86 | |||
87 | if (name == NULL) |
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88 | str[0] = '\0'; |
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89 | else {
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90 | error = copyinstr(name, str, MAXOBJNAME); |
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91 | if (error)
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92 | return error;
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93 | |||
94 | /* Check capability if name is protected object. */
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95 | if (name[0] == '!' && !task_capable(CAP_PROTSERV)) |
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96 | return EPERM;
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97 | } |
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98 | sched_lock(); |
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99 | |||
100 | if (curtask->nobjects >= MAXOBJECTS) {
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101 | sched_unlock(); |
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102 | return EAGAIN;
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103 | } |
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104 | /*
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105 | * Check user buffer first. This can reduce the error
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106 | * recovery for the subsequence resource allocations.
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107 | */
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108 | if (copyout(&obj, objp, sizeof(obj))) { |
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109 | sched_unlock(); |
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110 | return EFAULT;
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111 | } |
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112 | if (object_find(str) != NULL) { |
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113 | sched_unlock(); |
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114 | return EEXIST;
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115 | } |
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116 | if ((obj = kmem_alloc(sizeof(*obj))) == NULL) { |
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117 | sched_unlock(); |
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118 | return ENOMEM;
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119 | } |
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120 | if (name != NULL) |
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121 | strlcpy(obj->name, str, MAXOBJNAME); |
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122 | |||
123 | obj->owner = curtask; |
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124 | queue_init(&obj->sendq); |
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125 | queue_init(&obj->recvq); |
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126 | list_insert(&curtask->objects, &obj->task_link); |
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127 | curtask->nobjects++; |
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128 | list_insert(&object_list, &obj->link); |
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129 | copyout(&obj, objp, sizeof(obj));
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130 | |||
131 | sched_unlock(); |
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132 | return 0; |
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133 | } |
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134 | |||
135 | /*
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136 | * Search an object in the object name space. The object
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137 | * name must be null-terminated string.
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138 | */
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139 | int
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140 | object_lookup(const char *name, object_t *objp) |
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141 | { |
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142 | object_t obj; |
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143 | char str[MAXOBJNAME];
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144 | int error;
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145 | |||
146 | error = copyinstr(name, str, MAXOBJNAME); |
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147 | if (error)
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148 | return error;
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149 | |||
150 | sched_lock(); |
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151 | obj = object_find(str); |
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152 | sched_unlock(); |
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153 | |||
154 | if (obj == NULL) |
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155 | return ENOENT;
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156 | |||
157 | if (copyout(&obj, objp, sizeof(obj))) |
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158 | return EFAULT;
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159 | return 0; |
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160 | } |
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161 | |||
162 | int
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163 | object_valid(object_t obj) |
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164 | { |
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165 | object_t tmp; |
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166 | list_t n; |
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167 | |||
168 | for (n = list_first(&object_list); n != &object_list;
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169 | n = list_next(n)) { |
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170 | tmp = list_entry(n, struct object, link);
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171 | if (tmp == obj)
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172 | return 1; |
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173 | } |
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174 | return 0; |
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175 | } |
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176 | |||
177 | static object_t
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178 | object_find(const char *name) |
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179 | { |
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180 | object_t obj; |
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181 | list_t n; |
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182 | |||
183 | for (n = list_first(&object_list); n != &object_list;
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184 | n = list_next(n)) { |
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185 | obj = list_entry(n, struct object, link);
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186 | if (!strncmp(obj->name, name, MAXOBJNAME))
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187 | return obj;
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188 | } |
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189 | return 0; |
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190 | } |
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191 | |||
192 | /*
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193 | * Deallocate an object-- the internal version of object_destory.
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194 | */
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195 | static void |
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196 | object_deallocate(object_t obj) |
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197 | { |
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198 | |||
199 | msg_abort(obj); |
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200 | obj->owner->nobjects--; |
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201 | list_remove(&obj->task_link); |
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202 | list_remove(&obj->link); |
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203 | kmem_free(obj); |
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204 | } |
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205 | |||
206 | /*
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207 | * Destroy an object.
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208 | *
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209 | * All pending messages related to the target object are
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210 | * automatically cancelled.
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211 | */
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212 | int
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213 | object_destroy(object_t obj) |
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214 | { |
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215 | |||
216 | sched_lock(); |
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217 | if (!object_valid(obj)) {
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218 | sched_unlock(); |
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219 | return EINVAL;
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220 | } |
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221 | if (obj->owner != curtask) {
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222 | sched_unlock(); |
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223 | return EACCES;
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224 | } |
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225 | object_deallocate(obj); |
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226 | sched_unlock(); |
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227 | return 0; |
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228 | } |
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229 | |||
230 | /*
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231 | * Clean up for task termination.
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232 | */
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233 | void
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234 | object_cleanup(task_t task) |
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235 | { |
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236 | object_t obj; |
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237 | |||
238 | while (!list_empty(&task->objects)) {
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239 | obj = list_entry(list_first(&task->objects), |
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240 | struct object, task_link);
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241 | object_deallocate(obj); |
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242 | } |
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243 | } |
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244 | |||
245 | void
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246 | object_init(void)
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247 | { |
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248 | |||
249 | list_init(&object_list); |
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250 | } |