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Diffstat (limited to 'list.h')
| -rw-r--r-- | list.h | 219 |
1 files changed, 219 insertions, 0 deletions
@@ -0,0 +1,219 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copied from the Linux kernel source tree, version 2.6.13. + * + * Licensed under the GPL v2 as per the whole kernel source tree. + * + */ + +/** \file list.h doubly linked list implementation */ + +#include <stddef.h> /* offsetof */ + +/** get the struct this entry is embedded in */ +#define container_of(ptr, type, member) ({ \ + const typeof( ((type *)0)->member ) *__mptr = (ptr); \ + (type *)( (char *)__mptr - offsetof(type,member) );}) + +/** + * Non-NULL pointers that will result in page faults under normal + * circumstances, used to verify that nobody uses non-initialized list entries. + * Used for poisoning the \a next pointer of struct list_head. + */ +#define LIST_POISON1 ((void *) 0x00100100) +/** Non-null pointer, used for poisoning the \a prev pointer of struct + * list_head + */ +#define LIST_POISON2 ((void *) 0x00200200) + +/** Simple doubly linked list implementation. */ +struct list_head { + /** pointer to the next list entry */ + struct list_head *next; + /** pointer to the previous list entry */ + struct list_head *prev; +}; + +/** Define an initialized list head. */ +#define INITIALIZED_LIST_HEAD(name) struct list_head name = { &(name), &(name) } + + +/** must be called before using any other list functions */ +#define INIT_LIST_HEAD(ptr) do { \ + (ptr)->next = (ptr); (ptr)->prev = (ptr); \ +} while (0) + + +/* + * Some of the internal functions ("__xxx") are useful when + * manipulating whole lists rather than single entries, as + * sometimes we already know the next/prev entries and we can + * generate better code by using them directly rather than + * using the generic single-entry routines. + */ + + +/* + * Insert a new entry between two known consecutive entries. + * + * This is only for internal list manipulation where we know + * the prev/next entries already! + */ +static inline void __list_add(struct list_head *new, + struct list_head *prev, + struct list_head *next) +{ + next->prev = new; + new->next = next; + new->prev = prev; + prev->next = new; +} + +/** + * add a new entry + * + * \param new new entry to be added + * \param head list head to add it after + * + * Insert a new entry after the specified head. + * This is good for implementing stacks. + */ +static inline void list_add(struct list_head *new, struct list_head *head) +{ + __list_add(new, head, head->next); +} + +/** + * add a new entry + * + * \param new new entry to be added + * \param head list head to add it before + * + * Insert a new entry before the specified head. + * This is useful for implementing queues. + */ +static inline void list_add_tail(struct list_head *new, struct list_head *head) +{ + __list_add(new, head->prev, head); +} + +/* + * Delete a list entry by making the prev/next entries + * point to each other. + * + * This is only for internal list manipulation where we know + * the prev/next entries already! + */ +static inline void __list_del(struct list_head * prev, struct list_head * next) +{ + next->prev = prev; + prev->next = next; +} + +/** + * Delete entry from list. + * + * \param entry the element to delete from the list. + * + * Note: list_empty on entry does not return true after this, the entry is + * in an undefined state. + */ +static inline void list_del(struct list_head *entry) +{ + __list_del(entry->prev, entry->next); + entry->next = LIST_POISON1; + entry->prev = LIST_POISON2; +} + +/** + * delete from one list and add as another's head + * + * \param list: the entry to move + * \param head: the head that will precede our entry + */ +static inline void list_move(struct list_head *list, struct list_head *head) +{ + __list_del(list->prev, list->next); + _list_add(list, head); +} + +/** + * test whether a list is empty + * + * \param head the list to test. + */ +static inline int list_empty(const struct list_head *head) +{ + return head->next == head; +} + +/** + * get the struct for this entry + * + * \param ptr the &struct list_head pointer. + * \param type the type of the struct this is embedded in. + * \param member the name of the list_struct within the struct. + */ +#define list_entry(ptr, type, member) \ + container_of(ptr, type, member) + +/** + * iterate over list of given type + * + * \param pos the type * to use as a loop counter. + * \param head the head for your list. + * \param member the name of the list_struct within the struct. + */ +#define list_for_each_entry(pos, head, member) \ + for (pos = list_entry((head)->next, typeof(*pos), member); \ + &pos->member != (head); \ + pos = list_entry(pos->member.next, typeof(*pos), member)) + +/** + * iterate over list of given type safe against removal of list entry + * + * \param pos the type * to use as a loop counter. + * \param n another type * to use as temporary storage + * \param head the head for your list. + * \param member the name of the list_struct within the struct. + */ +#define list_for_each_entry_safe(pos, n, head, member) \ + for (pos = list_entry((head)->next, typeof(*pos), member), \ + n = list_entry(pos->member.next, typeof(*pos), member); \ + &pos->member != (head); \ + pos = n, n = list_entry(n->member.next, typeof(*n), member)) +/** + * iterate backwards over list of given type safe against removal of list entry + * \param pos the type * to use as a loop counter. + * \param n another type * to use as temporary storage + * \param head the head for your list. + * \param member the name of the list_struct within the struct. + */ +#define list_for_each_entry_safe_reverse(pos, n, head, member) \ + for (pos = list_entry((head)->prev, typeof(*pos), member), \ + n = list_entry(pos->member.prev, typeof(*pos), member); \ + &pos->member != (head); \ + pos = n, n = list_entry(n->member.prev, typeof(*n), member)) + +/** + * Get the first element from a list + * \param ptr the list head to take the element from. + * \param type The type of the struct this is embedded in. + * \param member The name of the list_struct within the struct. + * + * Note that list is expected to be not empty. + */ +#define list_first_entry(ptr, type, member) \ + list_entry((ptr)->next, type, member) + +/** + * Test whether a list has just one entry. + * + * \param head The list to test. + */ +static inline int list_is_singular(const struct list_head *head) +{ + return !list_empty(head) && (head->next == head->prev); +} + |