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213 lines
5.9 KiB
213 lines
5.9 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef LIST_H |
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#define LIST_H |
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#include <stdbool.h> |
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#include <stddef.h> |
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/* Are two types/vars the same type (ignoring qualifiers)? */ |
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#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) |
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/** |
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* container_of - cast a member of a structure out to the containing structure |
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* @ptr: the pointer to the member. |
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* @type: the type of the container struct this is embedded in. |
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* @member: the name of the member within the struct. |
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* |
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*/ |
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#define container_of(ptr, type, member) ({ \ |
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void *__mptr = (void *)(ptr); \ |
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_Static_assert(__same_type(*(ptr), ((type *)0)->member) || \ |
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__same_type(*(ptr), void), \ |
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"pointer type mismatch in container_of()"); \ |
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((type *)(__mptr - offsetof(type, member))); }) |
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#define LIST_POISON1 ((void *) 0x100) |
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#define LIST_POISON2 ((void *) 0x122) |
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/* |
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* Circular doubly linked list implementation. |
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* |
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* Some of the internal functions ("__xxx") are useful when |
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* manipulating whole lists rather than single entries, as |
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* sometimes we already know the next/prev entries and we can |
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* generate better code by using them directly rather than |
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* using the generic single-entry routines. |
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*/ |
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struct list_head { |
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struct list_head *next, *prev; |
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}; |
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#define LIST_HEAD_INIT(name) { &(name), &(name) } |
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#define LIST_HEAD(name) \ |
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struct list_head name = LIST_HEAD_INIT(name) |
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/** |
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* INIT_LIST_HEAD - Initialize a list_head structure |
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* @list: list_head structure to be initialized. |
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* |
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* Initializes the list_head to point to itself. If it is a list header, |
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* the result is an empty list. |
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*/ |
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static inline void INIT_LIST_HEAD(struct list_head *list) |
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{ |
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list->next = list; |
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list->prev = list; |
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} |
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/* |
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* Insert a new entry between two known consecutive entries. |
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* |
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* This is only for internal list manipulation where we know |
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* the prev/next entries already! |
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*/ |
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static inline void __list_add(struct list_head *new, |
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struct list_head *prev, |
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struct list_head *next) |
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{ |
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next->prev = new; |
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new->next = next; |
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new->prev = prev; |
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prev->next = new; |
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} |
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/** |
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* list_add - add a new entry |
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* @new: new entry to be added |
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* @head: list head to add it after |
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* |
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* Insert a new entry after the specified head. |
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* This is good for implementing stacks. |
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*/ |
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static inline void list_add(struct list_head *new, struct list_head *head) |
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{ |
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__list_add(new, head, head->next); |
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} |
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/** |
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* list_add_tail - add a new entry |
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* @new: new entry to be added |
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* @head: list head to add it before |
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* |
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* Insert a new entry before the specified head. |
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* This is useful for implementing queues. |
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*/ |
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static inline void list_add_tail(struct list_head *new, struct list_head *head) |
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{ |
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__list_add(new, head->prev, head); |
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} |
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/* |
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* Delete a list entry by making the prev/next entries |
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* point to each other. |
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* |
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* This is only for internal list manipulation where we know |
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* the prev/next entries already! |
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*/ |
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static inline void __list_del(struct list_head *prev, struct list_head *next) |
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{ |
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next->prev = prev; |
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prev->next = next; |
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} |
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static inline void __list_del_entry(struct list_head *entry) |
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{ |
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__list_del(entry->prev, entry->next); |
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} |
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/** |
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* list_del - deletes entry from list. |
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* @entry: the element to delete from the list. |
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* Note: list_empty() on entry does not return true after this, the entry is |
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* in an undefined state. |
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*/ |
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static inline void list_del(struct list_head *entry) |
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{ |
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__list_del_entry(entry); |
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entry->next = LIST_POISON1; |
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entry->prev = LIST_POISON2; |
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} |
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/** |
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* list_is_head - tests whether @list is the list @head |
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* @list: the entry to test |
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* @head: the head of the list |
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*/ |
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static inline int list_is_head(const struct list_head *list, const struct list_head *head) |
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{ |
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return list == head; |
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} |
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/** |
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* list_empty - tests whether a list is empty |
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* @head: the list to test. |
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*/ |
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static inline int list_empty(const struct list_head *head) |
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{ |
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return head->next == head; |
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} |
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/** |
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* list_entry - get the struct for this entry |
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* @ptr: the &struct list_head pointer. |
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* @type: the type of the struct this is embedded in. |
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* @member: the name of the list_head within the struct. |
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*/ |
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#define list_entry(ptr, type, member) \ |
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container_of(ptr, type, member) |
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/** |
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* list_first_entry - get the first element from a list |
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* @ptr: the list head to take the element from. |
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* @type: the type of the struct this is embedded in. |
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* @member: the name of the list_head within the struct. |
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* |
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* Note, that list is expected to be not empty. |
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*/ |
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#define list_first_entry(ptr, type, member) \ |
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list_entry((ptr)->next, type, member) |
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/** |
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* list_next_entry - get the next element in list |
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* @pos: the type * to cursor |
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* @member: the name of the list_head within the struct. |
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*/ |
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#define list_next_entry(pos, member) \ |
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list_entry((pos)->member.next, typeof(*(pos)), member) |
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/** |
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* list_entry_is_head - test if the entry points to the head of the list |
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* @pos: the type * to cursor |
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* @head: the head for your list. |
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* @member: the name of the list_head within the struct. |
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*/ |
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#define list_entry_is_head(pos, head, member) \ |
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(&pos->member == (head)) |
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/** |
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* list_for_each_entry - iterate over list of given type |
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* @pos: the type * to use as a loop cursor. |
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* @head: the head for your list. |
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* @member: the name of the list_head within the struct. |
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*/ |
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#define list_for_each_entry(pos, head, member) \ |
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for (pos = list_first_entry(head, typeof(*pos), member); \ |
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!list_entry_is_head(pos, head, member); \ |
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pos = list_next_entry(pos, member)) |
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/** |
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* list_for_each_entry_safe - iterate over list of given type. Safe against removal of list entry |
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* @pos: the type * to use as a loop cursor. |
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* @n: another type * to use as temporary storage |
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* @head: the head for your list. |
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* @member: the name of the list_head within the struct. |
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*/ |
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#define list_for_each_entry_safe(pos, n, head, member) \ |
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for (pos = list_first_entry(head, typeof(*pos), member), \ |
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n = list_next_entry(pos, member); \ |
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!list_entry_is_head(pos, head, member); \ |
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pos = n, n = list_next_entry(n, member)) |
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#endif /* LIST_H */
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