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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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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 |
