| /* SPDX-License-Identifier: GPL-2.0 */ |
| #ifndef _LINUX_LIST_H |
| #define _LINUX_LIST_H |
| |
| #include <linux/container_of.h> |
| #include <linux/types.h> |
| #include <linux/stddef.h> |
| #include <linux/poison.h> |
| #include <linux/const.h> |
| |
| #include <asm/barrier.h> |
| |
| /* |
| * Circular doubly linked list implementation. |
| * |
| * 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. |
| */ |
| |
| #define LIST_HEAD_INIT(name) { &(name), &(name) } |
| |
| #define LIST_HEAD(name) \ |
| struct list_head name = LIST_HEAD_INIT(name) |
| |
| /** |
| * INIT_LIST_HEAD - Initialize a list_head structure |
| * @list: list_head structure to be initialized. |
| * |
| * Initializes the list_head to point to itself. If it is a list header, |
| * the result is an empty list. |
| */ |
| static inline void INIT_LIST_HEAD(struct list_head *list) |
| { |
| WRITE_ONCE(list->next, list); |
| list->prev = list; |
| } |
| |
| #ifdef CONFIG_DEBUG_LIST |
| extern bool __list_add_valid(struct list_head *new, |
| struct list_head *prev, |
| struct list_head *next); |
| extern bool __list_del_entry_valid(struct list_head *entry); |
| #else |
| static inline bool __list_add_valid(struct list_head *new, |
| struct list_head *prev, |
| struct list_head *next) |
| { |
| return true; |
| } |
| static inline bool __list_del_entry_valid(struct list_head *entry) |
| { |
| return true; |
| } |
| #endif |
| |
| /* |
| * 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) |
| { |
| if (!__list_add_valid(new, prev, next)) |
| return; |
| |
| next->prev = new; |
| new->next = next; |
| new->prev = prev; |
| WRITE_ONCE(prev->next, new); |
| } |
| |
| /** |
| * list_add - add a new entry |
| * @new: new entry to be added |
| * @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); |
| } |
| |
| |
| /** |
| * list_add_tail - add a new entry |
| * @new: new entry to be added |
| * @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; |
| WRITE_ONCE(prev->next, next); |
| } |
| |
| /* |
| * Delete a list entry and clear the 'prev' pointer. |
| * |
| * This is a special-purpose list clearing method used in the networking code |
| * for lists allocated as per-cpu, where we don't want to incur the extra |
| * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this |
| * needs to check the node 'prev' pointer instead of calling list_empty(). |
| */ |
| static inline void __list_del_clearprev(struct list_head *entry) |
| { |
| __list_del(entry->prev, entry->next); |
| entry->prev = NULL; |
| } |
| |
| static inline void __list_del_entry(struct list_head *entry) |
| { |
| if (!__list_del_entry_valid(entry)) |
| return; |
| |
| __list_del(entry->prev, entry->next); |
| } |
| |
| /** |
| * list_del - deletes entry from list. |
| * @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(entry); |
| entry->next = LIST_POISON1; |
| entry->prev = LIST_POISON2; |
| } |
| |
| /** |
| * list_replace - replace old entry by new one |
| * @old : the element to be replaced |
| * @new : the new element to insert |
| * |
| * If @old was empty, it will be overwritten. |
| */ |
| static inline void list_replace(struct list_head *old, |
| struct list_head *new) |
| { |
| new->next = old->next; |
| new->next->prev = new; |
| new->prev = old->prev; |
| new->prev->next = new; |
| } |
| |
| /** |
| * list_replace_init - replace old entry by new one and initialize the old one |
| * @old : the element to be replaced |
| * @new : the new element to insert |
| * |
| * If @old was empty, it will be overwritten. |
| */ |
| static inline void list_replace_init(struct list_head *old, |
| struct list_head *new) |
| { |
| list_replace(old, new); |
| INIT_LIST_HEAD(old); |
| } |
| |
| /** |
| * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position |
| * @entry1: the location to place entry2 |
| * @entry2: the location to place entry1 |
| */ |
| static inline void list_swap(struct list_head *entry1, |
| struct list_head *entry2) |
| { |
| struct list_head *pos = entry2->prev; |
| |
| list_del(entry2); |
| list_replace(entry1, entry2); |
| if (pos == entry1) |
| pos = entry2; |
| list_add(entry1, pos); |
| } |
| |
| /** |
| * list_del_init - deletes entry from list and reinitialize it. |
| * @entry: the element to delete from the list. |
| */ |
| static inline void list_del_init(struct list_head *entry) |
| { |
| __list_del_entry(entry); |
| INIT_LIST_HEAD(entry); |
| } |
| |
| /** |
| * list_move - delete from one list and add as another's head |
| * @list: the entry to move |
| * @head: the head that will precede our entry |
| */ |
| static inline void list_move(struct list_head *list, struct list_head *head) |
| { |
| __list_del_entry(list); |
| list_add(list, head); |
| } |
| |
| /** |
| * list_move_tail - delete from one list and add as another's tail |
| * @list: the entry to move |
| * @head: the head that will follow our entry |
| */ |
| static inline void list_move_tail(struct list_head *list, |
| struct list_head *head) |
| { |
| __list_del_entry(list); |
| list_add_tail(list, head); |
| } |
| |
| /** |
| * list_bulk_move_tail - move a subsection of a list to its tail |
| * @head: the head that will follow our entry |
| * @first: first entry to move |
| * @last: last entry to move, can be the same as first |
| * |
| * Move all entries between @first and including @last before @head. |
| * All three entries must belong to the same linked list. |
| */ |
| static inline void list_bulk_move_tail(struct list_head *head, |
| struct list_head *first, |
| struct list_head *last) |
| { |
| first->prev->next = last->next; |
| last->next->prev = first->prev; |
| |
| head->prev->next = first; |
| first->prev = head->prev; |
| |
| last->next = head; |
| head->prev = last; |
| } |
| |
| /** |
| * list_is_first -- tests whether @list is the first entry in list @head |
| * @list: the entry to test |
| * @head: the head of the list |
| */ |
| static inline int list_is_first(const struct list_head *list, |
| const struct list_head *head) |
| { |
| return list->prev == head; |
| } |
| |
| /** |
| * list_is_last - tests whether @list is the last entry in list @head |
| * @list: the entry to test |
| * @head: the head of the list |
| */ |
| static inline int list_is_last(const struct list_head *list, |
| const struct list_head *head) |
| { |
| return list->next == head; |
| } |
| |
| /** |
| * list_empty - tests whether a list is empty |
| * @head: the list to test. |
| */ |
| static inline int list_empty(const struct list_head *head) |
| { |
| return READ_ONCE(head->next) == head; |
| } |
| |
| /** |
| * list_del_init_careful - deletes entry from list and reinitialize it. |
| * @entry: the element to delete from the list. |
| * |
| * This is the same as list_del_init(), except designed to be used |
| * together with list_empty_careful() in a way to guarantee ordering |
| * of other memory operations. |
| * |
| * Any memory operations done before a list_del_init_careful() are |
| * guaranteed to be visible after a list_empty_careful() test. |
| */ |
| static inline void list_del_init_careful(struct list_head *entry) |
| { |
| __list_del_entry(entry); |
| entry->prev = entry; |
| smp_store_release(&entry->next, entry); |
| } |
| |
| /** |
| * list_empty_careful - tests whether a list is empty and not being modified |
| * @head: the list to test |
| * |
| * Description: |
| * tests whether a list is empty _and_ checks that no other CPU might be |
| * in the process of modifying either member (next or prev) |
| * |
| * NOTE: using list_empty_careful() without synchronization |
| * can only be safe if the only activity that can happen |
| * to the list entry is list_del_init(). Eg. it cannot be used |
| * if another CPU could re-list_add() it. |
| */ |
| static inline int list_empty_careful(const struct list_head *head) |
| { |
| struct list_head *next = smp_load_acquire(&head->next); |
| return (next == head) && (next == head->prev); |
| } |
| |
| /** |
| * list_rotate_left - rotate the list to the left |
| * @head: the head of the list |
| */ |
| static inline void list_rotate_left(struct list_head *head) |
| { |
| struct list_head *first; |
| |
| if (!list_empty(head)) { |
| first = head->next; |
| list_move_tail(first, head); |
| } |
| } |
| |
| /** |
| * list_rotate_to_front() - Rotate list to specific item. |
| * @list: The desired new front of the list. |
| * @head: The head of the list. |
| * |
| * Rotates list so that @list becomes the new front of the list. |
| */ |
| static inline void list_rotate_to_front(struct list_head *list, |
| struct list_head *head) |
| { |
| /* |
| * Deletes the list head from the list denoted by @head and |
| * places it as the tail of @list, this effectively rotates the |
| * list so that @list is at the front. |
| */ |
| list_move_tail(head, list); |
| } |
| |
| /** |
| * list_is_singular - tests whether a list has just one entry. |
| * @head: the list to test. |
| */ |
| static inline int list_is_singular(const struct list_head *head) |
| { |
| return !list_empty(head) && (head->next == head->prev); |
| } |
| |
| static inline void __list_cut_position(struct list_head *list, |
| struct list_head *head, struct list_head *entry) |
| { |
| struct list_head *new_first = entry->next; |
| list->next = head->next; |
| list->next->prev = list; |
| list->prev = entry; |
| entry->next = list; |
| head->next = new_first; |
| new_first->prev = head; |
| } |
| |
| /** |
| * list_cut_position - cut a list into two |
| * @list: a new list to add all removed entries |
| * @head: a list with entries |
| * @entry: an entry within head, could be the head itself |
| * and if so we won't cut the list |
| * |
| * This helper moves the initial part of @head, up to and |
| * including @entry, from @head to @list. You should |
| * pass on @entry an element you know is on @head. @list |
| * should be an empty list or a list you do not care about |
| * losing its data. |
| * |
| */ |
| static inline void list_cut_position(struct list_head *list, |
| struct list_head *head, struct list_head *entry) |
| { |
| if (list_empty(head)) |
| return; |
| if (list_is_singular(head) && |
| (head->next != entry && head != entry)) |
| return; |
| if (entry == head) |
| INIT_LIST_HEAD(list); |
| else |
| __list_cut_position(list, head, entry); |
| } |
| |
| /** |
| * list_cut_before - cut a list into two, before given entry |
| * @list: a new list to add all removed entries |
| * @head: a list with entries |
| * @entry: an entry within head, could be the head itself |
| * |
| * This helper moves the initial part of @head, up to but |
| * excluding @entry, from @head to @list. You should pass |
| * in @entry an element you know is on @head. @list should |
| * be an empty list or a list you do not care about losing |
| * its data. |
| * If @entry == @head, all entries on @head are moved to |
| * @list. |
| */ |
| static inline void list_cut_before(struct list_head *list, |
| struct list_head *head, |
| struct list_head *entry) |
| { |
| if (head->next == entry) { |
| INIT_LIST_HEAD(list); |
| return; |
| } |
| list->next = head->next; |
| list->next->prev = list; |
| list->prev = entry->prev; |
| list->prev->next = list; |
| head->next = entry; |
| entry->prev = head; |
| } |
| |
| static inline void __list_splice(const struct list_head *list, |
| struct list_head *prev, |
| struct list_head *next) |
| { |
| struct list_head *first = list->next; |
| struct list_head *last = list->prev; |
| |
| first->prev = prev; |
| prev->next = first; |
| |
| last->next = next; |
| next->prev = last; |
| } |
| |
| /** |
| * list_splice - join two lists, this is designed for stacks |
| * @list: the new list to add. |
| * @head: the place to add it in the first list. |
| */ |
| static inline void list_splice(const struct list_head *list, |
| struct list_head *head) |
| { |
| if (!list_empty(list)) |
| __list_splice(list, head, head->next); |
| } |
| |
| /** |
| * list_splice_tail - join two lists, each list being a queue |
| * @list: the new list to add. |
| * @head: the place to add it in the first list. |
| */ |
| static inline void list_splice_tail(struct list_head *list, |
| struct list_head *head) |
| { |
| if (!list_empty(list)) |
| __list_splice(list, head->prev, head); |
| } |
| |
| /** |
| * list_splice_init - join two lists and reinitialise the emptied list. |
| * @list: the new list to add. |
| * @head: the place to add it in the first list. |
| * |
| * The list at @list is reinitialised |
| */ |
| static inline void list_splice_init(struct list_head *list, |
| struct list_head *head) |
| { |
| if (!list_empty(list)) { |
| __list_splice(list, head, head->next); |
| INIT_LIST_HEAD(list); |
| } |
| } |
| |
| /** |
| * list_splice_tail_init - join two lists and reinitialise the emptied list |
| * @list: the new list to add. |
| * @head: the place to add it in the first list. |
| * |
| * Each of the lists is a queue. |
| * The list at @list is reinitialised |
| */ |
| static inline void list_splice_tail_init(struct list_head *list, |
| struct list_head *head) |
| { |
| if (!list_empty(list)) { |
| __list_splice(list, head->prev, head); |
| INIT_LIST_HEAD(list); |
| } |
| } |
| |
| /** |
| * list_entry - get the struct for this entry |
| * @ptr: the &struct list_head pointer. |
| * @type: the type of the struct this is embedded in. |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_entry(ptr, type, member) \ |
| container_of(ptr, type, member) |
| |
| /** |
| * list_first_entry - get the first element from a list |
| * @ptr: the list head to take the element from. |
| * @type: the type of the struct this is embedded in. |
| * @member: the name of the list_head 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) |
| |
| /** |
| * list_last_entry - get the last element from a list |
| * @ptr: the list head to take the element from. |
| * @type: the type of the struct this is embedded in. |
| * @member: the name of the list_head within the struct. |
| * |
| * Note, that list is expected to be not empty. |
| */ |
| #define list_last_entry(ptr, type, member) \ |
| list_entry((ptr)->prev, type, member) |
| |
| /** |
| * list_first_entry_or_null - get the first element from a list |
| * @ptr: the list head to take the element from. |
| * @type: the type of the struct this is embedded in. |
| * @member: the name of the list_head within the struct. |
| * |
| * Note that if the list is empty, it returns NULL. |
| */ |
| #define list_first_entry_or_null(ptr, type, member) ({ \ |
| struct list_head *head__ = (ptr); \ |
| struct list_head *pos__ = READ_ONCE(head__->next); \ |
| pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ |
| }) |
| |
| /** |
| * list_next_entry - get the next element in list |
| * @pos: the type * to cursor |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_next_entry(pos, member) \ |
| list_entry((pos)->member.next, typeof(*(pos)), member) |
| |
| /** |
| * list_prev_entry - get the prev element in list |
| * @pos: the type * to cursor |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_prev_entry(pos, member) \ |
| list_entry((pos)->member.prev, typeof(*(pos)), member) |
| |
| /** |
| * list_for_each - iterate over a list |
| * @pos: the &struct list_head to use as a loop cursor. |
| * @head: the head for your list. |
| */ |
| #define list_for_each(pos, head) \ |
| for (pos = (head)->next; pos != (head); pos = pos->next) |
| |
| /** |
| * list_for_each_continue - continue iteration over a list |
| * @pos: the &struct list_head to use as a loop cursor. |
| * @head: the head for your list. |
| * |
| * Continue to iterate over a list, continuing after the current position. |
| */ |
| #define list_for_each_continue(pos, head) \ |
| for (pos = pos->next; pos != (head); pos = pos->next) |
| |
| /** |
| * list_for_each_prev - iterate over a list backwards |
| * @pos: the &struct list_head to use as a loop cursor. |
| * @head: the head for your list. |
| */ |
| #define list_for_each_prev(pos, head) \ |
| for (pos = (head)->prev; pos != (head); pos = pos->prev) |
| |
| /** |
| * list_for_each_safe - iterate over a list safe against removal of list entry |
| * @pos: the &struct list_head to use as a loop cursor. |
| * @n: another &struct list_head to use as temporary storage |
| * @head: the head for your list. |
| */ |
| #define list_for_each_safe(pos, n, head) \ |
| for (pos = (head)->next, n = pos->next; pos != (head); \ |
| pos = n, n = pos->next) |
| |
| /** |
| * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry |
| * @pos: the &struct list_head to use as a loop cursor. |
| * @n: another &struct list_head to use as temporary storage |
| * @head: the head for your list. |
| */ |
| #define list_for_each_prev_safe(pos, n, head) \ |
| for (pos = (head)->prev, n = pos->prev; \ |
| pos != (head); \ |
| pos = n, n = pos->prev) |
| |
| /** |
| * list_entry_is_head - test if the entry points to the head of the list |
| * @pos: the type * to cursor |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_entry_is_head(pos, head, member) \ |
| (&pos->member == (head)) |
| |
| /** |
| * list_for_each_entry - iterate over list of given type |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_for_each_entry(pos, head, member) \ |
| for (pos = list_first_entry(head, typeof(*pos), member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = list_next_entry(pos, member)) |
| |
| /** |
| * list_for_each_entry_reverse - iterate backwards over list of given type. |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_for_each_entry_reverse(pos, head, member) \ |
| for (pos = list_last_entry(head, typeof(*pos), member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = list_prev_entry(pos, member)) |
| |
| /** |
| * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue() |
| * @pos: the type * to use as a start point |
| * @head: the head of the list |
| * @member: the name of the list_head within the struct. |
| * |
| * Prepares a pos entry for use as a start point in list_for_each_entry_continue(). |
| */ |
| #define list_prepare_entry(pos, head, member) \ |
| ((pos) ? : list_entry(head, typeof(*pos), member)) |
| |
| /** |
| * list_for_each_entry_continue - continue iteration over list of given type |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Continue to iterate over list of given type, continuing after |
| * the current position. |
| */ |
| #define list_for_each_entry_continue(pos, head, member) \ |
| for (pos = list_next_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = list_next_entry(pos, member)) |
| |
| /** |
| * list_for_each_entry_continue_reverse - iterate backwards from the given point |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Start to iterate over list of given type backwards, continuing after |
| * the current position. |
| */ |
| #define list_for_each_entry_continue_reverse(pos, head, member) \ |
| for (pos = list_prev_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = list_prev_entry(pos, member)) |
| |
| /** |
| * list_for_each_entry_from - iterate over list of given type from the current point |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Iterate over list of given type, continuing from current position. |
| */ |
| #define list_for_each_entry_from(pos, head, member) \ |
| for (; !list_entry_is_head(pos, head, member); \ |
| pos = list_next_entry(pos, member)) |
| |
| /** |
| * list_for_each_entry_from_reverse - iterate backwards over list of given type |
| * from the current point |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Iterate backwards over list of given type, continuing from current position. |
| */ |
| #define list_for_each_entry_from_reverse(pos, head, member) \ |
| for (; !list_entry_is_head(pos, head, member); \ |
| pos = list_prev_entry(pos, member)) |
| |
| /** |
| * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry |
| * @pos: the type * to use as a loop cursor. |
| * @n: another type * to use as temporary storage |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| */ |
| #define list_for_each_entry_safe(pos, n, head, member) \ |
| for (pos = list_first_entry(head, typeof(*pos), member), \ |
| n = list_next_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = n, n = list_next_entry(n, member)) |
| |
| /** |
| * list_for_each_entry_safe_continue - continue list iteration safe against removal |
| * @pos: the type * to use as a loop cursor. |
| * @n: another type * to use as temporary storage |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Iterate over list of given type, continuing after current point, |
| * safe against removal of list entry. |
| */ |
| #define list_for_each_entry_safe_continue(pos, n, head, member) \ |
| for (pos = list_next_entry(pos, member), \ |
| n = list_next_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = n, n = list_next_entry(n, member)) |
| |
| /** |
| * list_for_each_entry_safe_from - iterate over list from current point safe against removal |
| * @pos: the type * to use as a loop cursor. |
| * @n: another type * to use as temporary storage |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Iterate over list of given type from current point, safe against |
| * removal of list entry. |
| */ |
| #define list_for_each_entry_safe_from(pos, n, head, member) \ |
| for (n = list_next_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = n, n = list_next_entry(n, member)) |
| |
| /** |
| * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal |
| * @pos: the type * to use as a loop cursor. |
| * @n: another type * to use as temporary storage |
| * @head: the head for your list. |
| * @member: the name of the list_head within the struct. |
| * |
| * Iterate backwards over list of given type, safe against removal |
| * of list entry. |
| */ |
| #define list_for_each_entry_safe_reverse(pos, n, head, member) \ |
| for (pos = list_last_entry(head, typeof(*pos), member), \ |
| n = list_prev_entry(pos, member); \ |
| !list_entry_is_head(pos, head, member); \ |
| pos = n, n = list_prev_entry(n, member)) |
| |
| /** |
| * list_safe_reset_next - reset a stale list_for_each_entry_safe loop |
| * @pos: the loop cursor used in the list_for_each_entry_safe loop |
| * @n: temporary storage used in list_for_each_entry_safe |
| * @member: the name of the list_head within the struct. |
| * |
| * list_safe_reset_next is not safe to use in general if the list may be |
| * modified concurrently (eg. the lock is dropped in the loop body). An |
| * exception to this is if the cursor element (pos) is pinned in the list, |
| * and list_safe_reset_next is called after re-taking the lock and before |
| * completing the current iteration of the loop body. |
| */ |
| #define list_safe_reset_next(pos, n, member) \ |
| n = list_next_entry(pos, member) |
| |
| /* |
| * Double linked lists with a single pointer list head. |
| * Mostly useful for hash tables where the two pointer list head is |
| * too wasteful. |
| * You lose the ability to access the tail in O(1). |
| */ |
| |
| #define HLIST_HEAD_INIT { .first = NULL } |
| #define HLIST_HEAD(name) struct hlist_head name = { .first = NULL } |
| #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL) |
| static inline void INIT_HLIST_NODE(struct hlist_node *h) |
| { |
| h->next = NULL; |
| h->pprev = NULL; |
| } |
| |
| /** |
| * hlist_unhashed - Has node been removed from list and reinitialized? |
| * @h: Node to be checked |
| * |
| * Not that not all removal functions will leave a node in unhashed |
| * state. For example, hlist_nulls_del_init_rcu() does leave the |
| * node in unhashed state, but hlist_nulls_del() does not. |
| */ |
| static inline int hlist_unhashed(const struct hlist_node *h) |
| { |
| return !h->pprev; |
| } |
| |
| /** |
| * hlist_unhashed_lockless - Version of hlist_unhashed for lockless use |
| * @h: Node to be checked |
| * |
| * This variant of hlist_unhashed() must be used in lockless contexts |
| * to avoid potential load-tearing. The READ_ONCE() is paired with the |
| * various WRITE_ONCE() in hlist helpers that are defined below. |
| */ |
| static inline int hlist_unhashed_lockless(const struct hlist_node *h) |
| { |
| return !READ_ONCE(h->pprev); |
| } |
| |
| /** |
| * hlist_empty - Is the specified hlist_head structure an empty hlist? |
| * @h: Structure to check. |
| */ |
| static inline int hlist_empty(const struct hlist_head *h) |
| { |
| return !READ_ONCE(h->first); |
| } |
| |
| static inline void __hlist_del(struct hlist_node *n) |
| { |
| struct hlist_node *next = n->next; |
| struct hlist_node **pprev = n->pprev; |
| |
| WRITE_ONCE(*pprev, next); |
| if (next) |
| WRITE_ONCE(next->pprev, pprev); |
| } |
| |
| /** |
| * hlist_del - Delete the specified hlist_node from its list |
| * @n: Node to delete. |
| * |
| * Note that this function leaves the node in hashed state. Use |
| * hlist_del_init() or similar instead to unhash @n. |
| */ |
| static inline void hlist_del(struct hlist_node *n) |
| { |
| __hlist_del(n); |
| n->next = LIST_POISON1; |
| n->pprev = LIST_POISON2; |
| } |
| |
| /** |
| * hlist_del_init - Delete the specified hlist_node from its list and initialize |
| * @n: Node to delete. |
| * |
| * Note that this function leaves the node in unhashed state. |
| */ |
| static inline void hlist_del_init(struct hlist_node *n) |
| { |
| if (!hlist_unhashed(n)) { |
| __hlist_del(n); |
| INIT_HLIST_NODE(n); |
| } |
| } |
| |
| /** |
| * hlist_add_head - add a new entry at the beginning of the hlist |
| * @n: new entry to be added |
| * @h: hlist head to add it after |
| * |
| * Insert a new entry after the specified head. |
| * This is good for implementing stacks. |
| */ |
| static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) |
| { |
| struct hlist_node *first = h->first; |
| WRITE_ONCE(n->next, first); |
| if (first) |
| WRITE_ONCE(first->pprev, &n->next); |
| WRITE_ONCE(h->first, n); |
| WRITE_ONCE(n->pprev, &h->first); |
| } |
| |
| /** |
| * hlist_add_before - add a new entry before the one specified |
| * @n: new entry to be added |
| * @next: hlist node to add it before, which must be non-NULL |
| */ |
| static inline void hlist_add_before(struct hlist_node *n, |
| struct hlist_node *next) |
| { |
| WRITE_ONCE(n->pprev, next->pprev); |
| WRITE_ONCE(n->next, next); |
| WRITE_ONCE(next->pprev, &n->next); |
| WRITE_ONCE(*(n->pprev), n); |
| } |
| |
| /** |
| * hlist_add_behind - add a new entry after the one specified |
| * @n: new entry to be added |
| * @prev: hlist node to add it after, which must be non-NULL |
| */ |
| static inline void hlist_add_behind(struct hlist_node *n, |
| struct hlist_node *prev) |
| { |
| WRITE_ONCE(n->next, prev->next); |
| WRITE_ONCE(prev->next, n); |
| WRITE_ONCE(n->pprev, &prev->next); |
| |
| if (n->next) |
| WRITE_ONCE(n->next->pprev, &n->next); |
| } |
| |
| /** |
| * hlist_add_fake - create a fake hlist consisting of a single headless node |
| * @n: Node to make a fake list out of |
| * |
| * This makes @n appear to be its own predecessor on a headless hlist. |
| * The point of this is to allow things like hlist_del() to work correctly |
| * in cases where there is no list. |
| */ |
| static inline void hlist_add_fake(struct hlist_node *n) |
| { |
| n->pprev = &n->next; |
| } |
| |
| /** |
| * hlist_fake: Is this node a fake hlist? |
| * @h: Node to check for being a self-referential fake hlist. |
| */ |
| static inline bool hlist_fake(struct hlist_node *h) |
| { |
| return h->pprev == &h->next; |
| } |
| |
| /** |
| * hlist_is_singular_node - is node the only element of the specified hlist? |
| * @n: Node to check for singularity. |
| * @h: Header for potentially singular list. |
| * |
| * Check whether the node is the only node of the head without |
| * accessing head, thus avoiding unnecessary cache misses. |
| */ |
| static inline bool |
| hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h) |
| { |
| return !n->next && n->pprev == &h->first; |
| } |
| |
| /** |
| * hlist_move_list - Move an hlist |
| * @old: hlist_head for old list. |
| * @new: hlist_head for new list. |
| * |
| * Move a list from one list head to another. Fixup the pprev |
| * reference of the first entry if it exists. |
| */ |
| static inline void hlist_move_list(struct hlist_head *old, |
| struct hlist_head *new) |
| { |
| new->first = old->first; |
| if (new->first) |
| new->first->pprev = &new->first; |
| old->first = NULL; |
| } |
| |
| #define hlist_entry(ptr, type, member) container_of(ptr,type,member) |
| |
| #define hlist_for_each(pos, head) \ |
| for (pos = (head)->first; pos ; pos = pos->next) |
| |
| #define hlist_for_each_safe(pos, n, head) \ |
| for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ |
| pos = n) |
| |
| #define hlist_entry_safe(ptr, type, member) \ |
| ({ typeof(ptr) ____ptr = (ptr); \ |
| ____ptr ? hlist_entry(____ptr, type, member) : NULL; \ |
| }) |
| |
| /** |
| * hlist_for_each_entry - iterate over list of given type |
| * @pos: the type * to use as a loop cursor. |
| * @head: the head for your list. |
| * @member: the name of the hlist_node within the struct. |
| */ |
| #define hlist_for_each_entry(pos, head, member) \ |
| for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\ |
| pos; \ |
| pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_continue - iterate over a hlist continuing after current point |
| * @pos: the type * to use as a loop cursor. |
| * @member: the name of the hlist_node within the struct. |
| */ |
| #define hlist_for_each_entry_continue(pos, member) \ |
| for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\ |
| pos; \ |
| pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_from - iterate over a hlist continuing from current point |
| * @pos: the type * to use as a loop cursor. |
| * @member: the name of the hlist_node within the struct. |
| */ |
| #define hlist_for_each_entry_from(pos, member) \ |
| for (; pos; \ |
| pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member)) |
| |
| /** |
| * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry |
| * @pos: the type * to use as a loop cursor. |
| * @n: a &struct hlist_node to use as temporary storage |
| * @head: the head for your list. |
| * @member: the name of the hlist_node within the struct. |
| */ |
| #define hlist_for_each_entry_safe(pos, n, head, member) \ |
| for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\ |
| pos && ({ n = pos->member.next; 1; }); \ |
| pos = hlist_entry_safe(n, typeof(*pos), member)) |
| |
| #endif |