1 | #if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD)
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2 | #define _BLKID_LIST_H
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3 |
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4 | #ifdef __cplusplus
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5 | extern "C" {
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6 | #endif
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7 |
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8 | #ifdef __GNUC__
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9 | #define _INLINE_ static __inline__
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10 | #else /* For Watcom C */
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11 | #define _INLINE_ static inline
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12 | #endif
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13 |
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14 | /*
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15 | * Simple doubly linked list implementation.
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16 | *
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17 | * Some of the internal functions ("__xxx") are useful when
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18 | * manipulating whole lists rather than single entries, as
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19 | * sometimes we already know the next/prev entries and we can
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20 | * generate better code by using them directly rather than
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21 | * using the generic single-entry routines.
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22 | */
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23 |
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24 | struct list_head {
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25 | struct list_head *next, *prev;
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26 | };
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27 |
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28 | #define LIST_HEAD_INIT(name) { &(name), &(name) }
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29 |
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30 | #define LIST_HEAD(name) \
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31 | struct list_head name = LIST_HEAD_INIT(name)
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32 |
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33 | #define INIT_LIST_HEAD(ptr) do { \
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34 | (ptr)->next = (ptr); (ptr)->prev = (ptr); \
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35 | } while (0)
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36 |
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37 | /*
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38 | * Insert a new entry between two known consecutive entries.
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39 | *
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40 | * This is only for internal list manipulation where we know
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41 | * the prev/next entries already!
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42 | */
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43 | _INLINE_ void __list_add(struct list_head * add,
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44 | struct list_head * prev,
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45 | struct list_head * next)
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46 | {
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47 | next->prev = add;
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48 | add->next = next;
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49 | add->prev = prev;
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50 | prev->next = add;
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51 | }
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52 |
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53 | /**
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54 | * list_add - add a new entry
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55 | * @add: new entry to be added
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56 | * @head: list head to add it after
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57 | *
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58 | * Insert a new entry after the specified head.
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59 | * This is good for implementing stacks.
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60 | */
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61 | _INLINE_ void list_add(struct list_head *add, struct list_head *head)
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62 | {
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63 | __list_add(add, head, head->next);
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64 | }
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65 |
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66 | /**
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67 | * list_add_tail - add a new entry
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68 | * @add: new entry to be added
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69 | * @head: list head to add it before
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70 | *
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71 | * Insert a new entry before the specified head.
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72 | * This is useful for implementing queues.
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73 | */
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74 | _INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
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75 | {
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76 | __list_add(add, head->prev, head);
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77 | }
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78 |
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79 | /*
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80 | * Delete a list entry by making the prev/next entries
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81 | * point to each other.
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82 | *
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83 | * This is only for internal list manipulation where we know
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84 | * the prev/next entries already!
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85 | */
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86 | _INLINE_ void __list_del(struct list_head * prev,
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87 | struct list_head * next)
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88 | {
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89 | next->prev = prev;
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90 | prev->next = next;
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91 | }
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92 |
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93 | /**
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94 | * list_del - deletes entry from list.
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95 | * @entry: the element to delete from the list.
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96 | *
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97 | * list_empty() on @entry does not return true after this, @entry is
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98 | * in an undefined state.
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99 | */
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100 | _INLINE_ void list_del(struct list_head *entry)
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101 | {
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102 | __list_del(entry->prev, entry->next);
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103 | }
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104 |
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105 | /**
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106 | * list_del_init - deletes entry from list and reinitialize it.
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107 | * @entry: the element to delete from the list.
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108 | */
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109 | _INLINE_ void list_del_init(struct list_head *entry)
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110 | {
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111 | __list_del(entry->prev, entry->next);
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112 | INIT_LIST_HEAD(entry);
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113 | }
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114 |
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115 | /**
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116 | * list_empty - tests whether a list is empty
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117 | * @head: the list to test.
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118 | */
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119 | _INLINE_ int list_empty(struct list_head *head)
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120 | {
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121 | return head->next == head;
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122 | }
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123 |
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124 | /**
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125 | * list_splice - join two lists
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126 | * @list: the new list to add.
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127 | * @head: the place to add it in the first list.
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128 | */
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129 | _INLINE_ void list_splice(struct list_head *list, struct list_head *head)
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130 | {
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131 | struct list_head *first = list->next;
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132 |
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133 | if (first != list) {
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134 | struct list_head *last = list->prev;
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135 | struct list_head *at = head->next;
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136 |
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137 | first->prev = head;
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138 | head->next = first;
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139 |
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140 | last->next = at;
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141 | at->prev = last;
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142 | }
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143 | }
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144 |
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145 | /**
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146 | * list_entry - get the struct for this entry
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147 | * @ptr: the &struct list_head pointer.
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148 | * @type: the type of the struct this is embedded in.
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149 | * @member: the name of the list_struct within the struct.
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150 | */
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151 | #define list_entry(ptr, type, member) \
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152 | ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
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153 |
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154 | /**
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155 | * list_for_each - iterate over elements in a list
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156 | * @pos: the &struct list_head to use as a loop counter.
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157 | * @head: the head for your list.
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158 | */
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159 | #define list_for_each(pos, head) \
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160 | for (pos = (head)->next; pos != (head); pos = pos->next)
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161 |
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162 | /**
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163 | * list_for_each_safe - iterate over elements in a list, but don't dereference
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164 | * pos after the body is done (in case it is freed)
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165 | * @pos: the &struct list_head to use as a loop counter.
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166 | * @pnext: the &struct list_head to use as a pointer to the next item.
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167 | * @head: the head for your list (not included in iteration).
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168 | */
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169 | #define list_for_each_safe(pos, pnext, head) \
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170 | for (pos = (head)->next, pnext = pos->next; pos != (head); \
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171 | pos = pnext, pnext = pos->next)
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172 |
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173 | #undef _INLINE_
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174 |
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175 | #ifdef __cplusplus
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176 | }
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177 | #endif
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178 |
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179 | #endif /* _BLKID_LIST_H */
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