1 #ifndef _LINUX_LIST_H 2 #define _LINUX_LIST_H 3 4 #ifndef ARCH_HAS_PREFETCH 5 #define ARCH_HAS_PREFETCH 6 static inline void prefetch(const void *x) {;} 7 #endif 8 9 /* 10 * Simple doubly linked list implementation. 11 * 12 * Some of the internal functions ("__xxx") are useful when 13 * manipulating whole lists rather than single entries, as 14 * sometimes we already know the next/prev entries and we can 15 * generate better code by using them directly rather than 16 * using the generic single-entry routines. 17 */ 18 19 struct list_head { 20 struct list_head *next, *prev; 21 }; 22 23 #define LIST_HEAD_INIT(name) { &(name), &(name) } 24 25 #define LIST_HEAD(name) \ 26 struct list_head name = LIST_HEAD_INIT(name) 27 28 #define INIT_LIST_HEAD(ptr) do { \ 29 (ptr)->next = (ptr); (ptr)->prev = (ptr); \ 30 } while (0) 31 32 /* 33 * Insert a new entry between two known consecutive entries. 34 * 35 * This is only for internal list manipulation where we know 36 * the prev/next entries already! 37 */ 38 static inline void __list_add(struct list_head *new, 39 struct list_head *prev, 40 struct list_head *next) 41 { 42 next->prev = new; 43 new->next = next; 44 new->prev = prev; 45 prev->next = new; 46 } 47 48 /** 49 * list_add - add a new entry 50 * @new: new entry to be added 51 * @head: list head to add it after 52 * 53 * Insert a new entry after the specified head. 54 * This is good for implementing stacks. 55 */ 56 static inline void list_add(struct list_head *new, struct list_head *head) 57 { 58 __list_add(new, head, head->next); 59 } 60 61 /** 62 * list_add_tail - add a new entry 63 * @new: new entry to be added 64 * @head: list head to add it before 65 * 66 * Insert a new entry before the specified head. 67 * This is useful for implementing queues. 68 */ 69 static inline void list_add_tail(struct list_head *new, struct list_head *head) 70 { 71 __list_add(new, head->prev, head); 72 } 73 74 /* 75 * Delete a list entry by making the prev/next entries 76 * point to each other. 77 * 78 * This is only for internal list manipulation where we know 79 * the prev/next entries already! 80 */ 81 static inline void __list_del(struct list_head *prev, struct list_head *next) 82 { 83 next->prev = prev; 84 prev->next = next; 85 } 86 87 /** 88 * list_del - deletes entry from list. 89 * @entry: the element to delete from the list. 90 * Note: list_empty on entry does not return true after this, the entry is in an undefined state. 91 */ 92 static inline void list_del(struct list_head *entry) 93 { 94 __list_del(entry->prev, entry->next); 95 entry->next = (void *) 0; 96 entry->prev = (void *) 0; 97 } 98 99 /** 100 * list_del_init - deletes entry from list and reinitialize it. 101 * @entry: the element to delete from the list. 102 */ 103 static inline void list_del_init(struct list_head *entry) 104 { 105 __list_del(entry->prev, entry->next); 106 INIT_LIST_HEAD(entry); 107 } 108 109 /** 110 * list_move - delete from one list and add as another's head 111 * @list: the entry to move 112 * @head: the head that will precede our entry 113 */ 114 static inline void list_move(struct list_head *list, struct list_head *head) 115 { 116 __list_del(list->prev, list->next); 117 list_add(list, head); 118 } 119 120 /** 121 * list_move_tail - delete from one list and add as another's tail 122 * @list: the entry to move 123 * @head: the head that will follow our entry 124 */ 125 static inline void list_move_tail(struct list_head *list, 126 struct list_head *head) 127 { 128 __list_del(list->prev, list->next); 129 list_add_tail(list, head); 130 } 131 132 /** 133 * list_empty - tests whether a list is empty 134 * @head: the list to test. 135 */ 136 static inline int list_empty(struct list_head *head) 137 { 138 return head->next == head; 139 } 140 141 static inline void __list_splice(struct list_head *list, 142 struct list_head *head) 143 { 144 struct list_head *first = list->next; 145 struct list_head *last = list->prev; 146 struct list_head *at = head->next; 147 148 first->prev = head; 149 head->next = first; 150 151 last->next = at; 152 at->prev = last; 153 } 154 155 /** 156 * list_splice - join two lists 157 * @list: the new list to add. 158 * @head: the place to add it in the first list. 159 */ 160 static inline void list_splice(struct list_head *list, struct list_head *head) 161 { 162 if (!list_empty(list)) 163 __list_splice(list, head); 164 } 165 166 /** 167 * list_splice_init - join two lists and reinitialise the emptied list. 168 * @list: the new list to add. 169 * @head: the place to add it in the first list. 170 * 171 * The list at @list is reinitialised 172 */ 173 static inline void list_splice_init(struct list_head *list, 174 struct list_head *head) 175 { 176 if (!list_empty(list)) { 177 __list_splice(list, head); 178 INIT_LIST_HEAD(list); 179 } 180 } 181 182 /** 183 * list_entry - get the struct for this entry 184 * @ptr: the &struct list_head pointer. 185 * @type: the type of the struct this is embedded in. 186 * @member: the name of the list_struct within the struct. 187 */ 188 #define list_entry(ptr, type, member) \ 189 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member))) 190 191 /** 192 * list_for_each - iterate over a list 193 * @pos: the &struct list_head to use as a loop counter. 194 * @head: the head for your list. 195 */ 196 #define list_for_each(pos, head) \ 197 for (pos = (head)->next, prefetch(pos->next); pos != (head); \ 198 pos = pos->next, prefetch(pos->next)) 199 /** 200 * list_for_each_prev - iterate over a list backwards 201 * @pos: the &struct list_head to use as a loop counter. 202 * @head: the head for your list. 203 */ 204 #define list_for_each_prev(pos, head) \ 205 for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \ 206 pos = pos->prev, prefetch(pos->prev)) 207 208 /** 209 * list_for_each_safe - iterate over a list safe against removal of list entry 210 * @pos: the &struct list_head to use as a loop counter. 211 * @n: another &struct list_head to use as temporary storage 212 * @head: the head for your list. 213 */ 214 #define list_for_each_safe(pos, n, head) \ 215 for (pos = (head)->next, n = pos->next; pos != (head); \ 216 pos = n, n = pos->next) 217 218 /** 219 * list_for_each_entry - iterate over list of given type 220 * @pos: the type * to use as a loop counter. 221 * @head: the head for your list. 222 * @member: the name of the list_struct within the struct. 223 */ 224 #define list_for_each_entry(pos, head, member) \ 225 for (pos = list_entry((head)->next, typeof(*pos), member), \ 226 prefetch(pos->member.next); \ 227 &pos->member != (head); \ 228 pos = list_entry(pos->member.next, typeof(*pos), member), \ 229 prefetch(pos->member.next)) 230 231 /** 232 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry 233 * @pos: the type * to use as a loop counter. 234 * @n: another type * to use as temporary storage 235 * @head: the head for your list. 236 * @member: the name of the list_struct within the struct. 237 */ 238 #define list_for_each_entry_safe(pos, n, head, member) \ 239 for (pos = list_entry((head)->next, typeof(*pos), member), \ 240 n = list_entry(pos->member.next, typeof(*pos), member); \ 241 &pos->member != (head); \ 242 pos = n, n = list_entry(n->member.next, typeof(*n), member)) 243 244 /** 245 * list_for_each_entry_continue - iterate over list of given type 246 * continuing after existing point 247 * @pos: the type * to use as a loop counter. 248 * @head: the head for your list. 249 * @member: the name of the list_struct within the struct. 250 */ 251 #define list_for_each_entry_continue(pos, head, member) \ 252 for (pos = list_entry(pos->member.next, typeof(*pos), member), \ 253 prefetch(pos->member.next); \ 254 &pos->member != (head); \ 255 pos = list_entry(pos->member.next, typeof(*pos), member), \ 256 prefetch(pos->member.next)) 257 258 #endif 259