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1 #ifndef _LINUX_LIST_H
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2 #define _LINUX_LIST_H
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3
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4 /*
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5 * Simple doubly linked list implementation.
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6 *
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7 * Some of the internal functions ("__xxx") are useful when
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8 * manipulating whole lists rather than single entries, as
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9 * sometimes we already know the next/prev entries and we can
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10 * generate better code by using them directly rather than
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11 * using the generic single-entry routines.
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12 */
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13
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14 struct list_head {
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15 struct list_head *next, *prev;
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16 };
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17
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18 #define LIST_HEAD_INIT(name) { &(name), &(name) }
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19
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20 #define LIST_HEAD(name) \
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21 struct list_head name = LIST_HEAD_INIT(name)
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22
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23 #define INIT_LIST_HEAD(ptr) do { \
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24 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
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25 } while (0)
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26
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27 /*
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28 * Insert a new entry between two known consecutive entries.
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29 *
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30 * This is only for internal list manipulation where we know
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31 * the prev/next entries already!
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32 */
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33 static inline void
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34 __list_add(struct list_head *new,
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35 struct list_head *prev, struct list_head *next)
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36 {
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37 next->prev = new;
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38 new->next = next;
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39 new->prev = prev;
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40 prev->next = new;
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41 }
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42
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43 /**
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44 * list_add - add a new entry
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45 * @new: new entry to be added
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46 * @head: list head to add it after
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47 *
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48 * Insert a new entry after the specified head.
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49 * This is good for implementing stacks.
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50 */
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51 static inline void list_add(struct list_head *new, struct list_head *head)
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52 {
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53 __list_add(new, head, head->next);
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54 }
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55
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56 /**
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57 * list_add_tail - add a new entry
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58 * @new: new entry to be added
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59 * @head: list head to add it before
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60 *
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61 * Insert a new entry before the specified head.
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62 * This is useful for implementing queues.
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63 */
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64 static inline void
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65 list_add_tail(struct list_head *new, struct list_head *head)
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66 {
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67 __list_add(new, head->prev, head);
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68 }
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69
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70 /*
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71 * Delete a list entry by making the prev/next entries
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72 * point to each other.
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73 *
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74 * This is only for internal list manipulation where we know
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75 * the prev/next entries already!
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76 */
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77 static inline void
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78 __list_del(struct list_head *prev, struct list_head *next)
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79 {
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80 next->prev = prev;
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81 prev->next = next;
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82 }
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83
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84 /**
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85 * list_del - deletes entry from list.
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86 * @entry: the element to delete from the list.
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87 * Note: list_empty on entry does not return true after this, the entry is
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88 * in an undefined state.
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89 */
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90 static inline void list_del(struct list_head *entry)
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91 {
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92 __list_del(entry->prev, entry->next);
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93 entry->next = (void *) 0;
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94 entry->prev = (void *) 0;
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95 }
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96
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97 /**
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98 * list_del_init - deletes entry from list and reinitialize it.
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99 * @entry: the element to delete from the list.
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100 */
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101 static inline void list_del_init(struct list_head *entry)
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102 {
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103 __list_del(entry->prev, entry->next);
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104 INIT_LIST_HEAD(entry);
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105 }
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106
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107 /**
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108 * list_move - delete from one list and add as another's head
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109 * @list: the entry to move
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110 * @head: the head that will precede our entry
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111 */
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112 static inline void
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113 list_move(struct list_head *list, struct list_head *head)
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114 {
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115 __list_del(list->prev, list->next);
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116 list_add(list, head);
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117 }
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118
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119 /**
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120 * list_move_tail - delete from one list and add as another's tail
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121 * @list: the entry to move
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122 * @head: the head that will follow our entry
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123 */
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124 static inline void
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125 list_move_tail(struct list_head *list, struct list_head *head)
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126 {
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127 __list_del(list->prev, list->next);
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128 list_add_tail(list, head);
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129 }
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130
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131 /**
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132 * list_empty - test whether a list is empty
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133 * @head: the list to test.
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134 */
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135 static inline int list_empty(struct list_head *head)
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136 {
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137 return head->next == head;
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138 }
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139
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140 static inline void
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141 __list_splice(struct list_head *list, struct list_head *head)
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142 {
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143 struct list_head *first = list->next;
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144 struct list_head *last = list->prev;
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145 struct list_head *at = head->next;
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146
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147 first->prev = head;
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148 head->next = first;
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149
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150 last->next = at;
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151 at->prev = last;
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152 }
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153
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154 /**
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155 * list_splice - join two lists
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156 * @list: the new list to add.
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157 * @head: the place to add it in the first list.
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158 */
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159 static inline void
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160 list_splice(struct list_head *list, struct list_head *head)
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161 {
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162 if (!list_empty(list))
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163 __list_splice(list, head);
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164 }
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165
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166 /**
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167 * list_splice_init - join two lists and reinitialise the emptied list.
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168 * @list: the new list to add.
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169 * @head: the place to add it in the first list.
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170 *
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171 * The list at @list is reinitialised
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172 */
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173 static inline void
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174 list_splice_init(struct list_head *list, struct list_head *head)
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175 {
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176 if (!list_empty(list)) {
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177 __list_splice(list, head);
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178 INIT_LIST_HEAD(list);
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179 }
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180 }
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181
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182 /**
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183 * list_entry - get the struct for this entry
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184 * @ptr: the &struct list_head pointer.
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185 * @type: the type of the struct this is embedded in.
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186 * @member: the name of the list_struct within the struct.
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187 */
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188 #define list_entry(ptr, type, member) \
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189 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
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190
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191 /**
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192 * list_for_each_safe - iterate over a list safe against removal of list entry
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193 * @pos: the &struct list_head to use as a loop counter.
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194 * @n: another &struct list_head to use as temporary storage
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195 * @head: the head for your list.
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196 */
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197 #define list_for_each_safe(pos, n, head) \
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198 for (pos = (head)->next, n = pos->next; pos != (head); \
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199 pos = n, n = pos->next)
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200
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201 /**
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28
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202 * list_for_each_entry_safe - iterate over list of given type safe against
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203 * removal of list entry
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204 * @pos: the type * to use as a loop counter.
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205 * @n: another type * to use as temporary storage
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206 * @head: the head for your list.
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207 * @member: the name of the list_struct within the struct.
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208 */
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209 #define list_for_each_entry_safe(pos, n, head, member) \
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210 for (pos = list_entry((head)->next, typeof(*pos), member), \
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211 n = list_entry(pos->member.next, typeof(*pos), member); \
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212 &pos->member != (head); \
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213 pos = n, n = list_entry(n->member.next, typeof(*n), member))
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214
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215 #endif
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