Viewing: list.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LIBCFS_UTIL_LIST_H__
#define __LIBCFS_UTIL_LIST_H__
/**
* DOC: Simple 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 prefetch(a) ((void)a)
struct list_head {
struct list_head *next, *prev;
};
#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define INIT_LIST_HEAD(ptr) do { \
(ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)
/*
* 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;
}
/**
* list_add() - Insert an entry at the start of a list.
* @new: new entry to be inserted
* @head: list to add it to
*
* Insert a new entry after the specified head.
* This is good for implementing stacks.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_add(struct list_head *new, struct list_head *head)
{
__list_add(new, head, head->next);
}
/**
* list_add_tail() - Insert an entry at the end of a list.
* @new: new entry to be inserted
* @head: list to add it to
*
* Insert a new entry before the specified head.
* This is useful for implementing queues.
*
* Return:
* * %void - Does not return any value
*/
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;
}
/**
* list_del() - Remove an entry from the list it is currently in.
* @entry: the entry to remove
*
* Note: list_empty(entry) does not return true after this,
* the entry is in an undefined state.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_del(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
}
/**
* list_del_init() - Remove entry from the list and reinitialize it.
* @entry: the entry to remove.
*
* Remove an entry from the list it is currently in and reinitialize it.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_del_init(struct list_head *entry)
{
__list_del(entry->prev, entry->next);
INIT_LIST_HEAD(entry);
}
/**
* list_move() - Remove entry and insert it at the start of another list
* @list: the entry to move
* @head: the list to move it to
*
* Remove an entry from the list it is currently in and insert
* it at the start
*
* Return:
* * %void - Does not return any value
*/
static inline void list_move(struct list_head *list, struct list_head *head)
{
__list_del(list->prev, list->next);
list_add(list, head);
}
/**
* list_move_tail() - Remove entry and insert it at the end of another list.
* @list: the entry to move
* @head: the list to move it to
*
* Remove an entry from the list it is currently in and insert
* it at the end of
*
* Return:
* * %void - Does not return any value
*/
static inline void list_move_tail(struct list_head *list,
struct list_head *head)
{
__list_del(list->prev, list->next);
list_add_tail(list, head);
}
/**
* list_empty() - Test whether a list is empty
* @head: the list to test.
*
* Return:
* * %void - Does not return any value
*/
static inline int list_empty(struct list_head *head)
{
return head->next == head;
}
/**
* list_empty_careful() - Test whether a list is empty and not being modified
* @head: the list to test
*
* 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.
*
* Return:
* * %void - Does not return any value
*/
static inline int list_empty_careful(const struct list_head *head)
{
struct list_head *next = head->next;
return (next == head) && (next == head->prev);
}
static inline void __list_splice(struct list_head *list, struct list_head *head)
{
struct list_head *first = list->next;
struct list_head *last = list->prev;
struct list_head *at = head->next;
first->prev = head;
head->next = first;
last->next = at;
at->prev = last;
}
/**
* list_splice() - Join two lists
* @list: the new list to add.
* @head: the place to add it in the first list.
*
* The contents of @list are added at the start of @head.
* @list is in an undefined state on return.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_splice(struct list_head *list, struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, head);
}
/**
* list_splice_tail() - Join two lists at the tail
* @list: the new list to add.
* @head: the place to add it in the first list.
*
* The contents of @list are added at the tail
* @list is in an undefined state on return.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_splice_tail(struct list_head *list,
struct list_head *head)
{
if (!list_empty(list))
__list_splice(list, head->prev);
}
/**
* 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 contents of @list are added at the start of @head.
* @list is empty on return.
*
* Return:
* * %void - Does not return any value
*/
static inline void list_splice_init(struct list_head *list,
struct list_head *head)
{
if (!list_empty(list)) {
__list_splice(list, head);
INIT_LIST_HEAD(list);
}
}
/**
* define list_entry - Get the container of a list
* @ptr: the embedded list.
* @type: the type of the struct this is embedded in.
* @member: the member name of the list within the struct.
*/
#define list_entry(ptr, type, member) \
((type *)((char *)(ptr)-(char *)(&((type *)0)->member)))
/**
* define 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)
/**
* define 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)
/**
* define list_for_each - Iterate over a list
* @pos: the iterator
* @head: the list to iterate over
*
* Behaviour is undefined if @pos is removed from the list in the body of the
* loop.
*/
#define list_for_each(pos, head) \
for (pos = (head)->next, prefetch(pos->next); pos != (head); \
pos = pos->next, prefetch(pos->next))
/**
* define list_for_each_safe - Iterate over a list safely
* @pos: the iterator
* @n: temporary storage
* @head: the list to iterate over
*
* This is safe to use if @pos could be removed from the list in the body of
* the loop.
*/
#define list_for_each_safe(pos, n, head) \
for (pos = (head)->next, n = pos->next; pos != (head); \
pos = n, n = pos->next)
/**
* define list_for_each_entry_continue - Iterate continuing after existing point
* @pos: the type * to use as a loop counter
* @head: the list head
* @member: the name of the list_struct within the struct
*
* Iterate over a list continuing after existing point
*/
#define list_for_each_entry_continue(pos, head, member) \
for (pos = list_entry(pos->member.next, typeof(*pos), member); \
prefetch(pos->member.next), &pos->member != (head); i \
pos = list_entry(pos->member.next, typeof(*pos), member))
/**
* DOC: hlist Hash List
* 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).
*/
/**
* struct hlist_node - node for hlist
* @next: next item
* @pprev: previous item
*/
struct hlist_node {
struct hlist_node *next, **pprev;
};
/**
* struct hlist_head - Head of list
* @first: head item
*/
struct hlist_head {
struct hlist_node *first;
};
/*
* "NULL" might not be defined at this point
*/
#ifdef NULL
#define NULL_P NULL
#else
#define NULL_P ((void *)0)
#endif
#define HLIST_HEAD_INIT { NULL_P }
#define HLIST_HEAD(name) struct hlist_head name = { NULL_P }
#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL_P)
#define INIT_HLIST_NODE(ptr) ((ptr)->next = NULL_P, (ptr)->pprev = NULL_P)
static inline int hlist_unhashed(const struct hlist_node *h)
{
return !h->pprev;
}
static inline int hlist_empty(const struct hlist_head *h)
{
return !h->first;
}
static inline void __hlist_del(struct hlist_node *n)
{
struct hlist_node *next = n->next;
struct hlist_node **pprev = n->pprev;
*pprev = next;
if (next)
next->pprev = pprev;
}
static inline void hlist_del(struct hlist_node *n)
{
__hlist_del(n);
}
static inline void hlist_del_init(struct hlist_node *n)
{
if (n->pprev) {
__hlist_del(n);
INIT_HLIST_NODE(n);
}
}
static inline void hlist_add_head(struct hlist_node *n,
struct hlist_head *h)
{
struct hlist_node *first = h->first;
n->next = first;
if (first)
first->pprev = &n->next;
h->first = n;
n->pprev = &h->first;
}
/* next must be != NULL */
static inline void hlist_add_before(struct hlist_node *n,
struct hlist_node *next)
{
n->pprev = next->pprev;
n->next = next;
next->pprev = &n->next;
*(n->pprev) = n;
}
static inline void hlist_add_after(struct hlist_node *n,
struct hlist_node *next)
{
next->next = n->next;
n->next = next;
next->pprev = &n->next;
if (next->next)
next->next->pprev = &next->next;
}
#define hlist_entry(ptr, type, member) container_of(ptr, type, member)
#define hlist_for_each(pos, head) \
for (pos = (head)->first; pos && (prefetch(pos->next), 1); \
pos = pos->next)
#define hlist_for_each_safe(pos, n, head) \
for (pos = (head)->first; pos && (n = pos->next, 1); \
pos = n)
/**
* define hlist_for_each_entry - Iterate over an hlist of given type
* @tpos: the type * to use as a loop counter.
* @pos: the &struct hlist_node to use as a loop counter.
* @head: the head for your list.
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry(tpos, pos, head, member) \
for (pos = (head)->first; \
pos && ({ prefetch(pos->next); 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
pos = pos->next)
/**
* define hlist_for_each_entry_continue - Iterate continuing after existing point
* @tpos: the type * to use as a loop counter.
* @pos: the &struct hlist_node to use as a loop counter.
* @member: the name of the hlist_node within the struct.
*
* Iterate over an hlist continuing after existing point
*/
#define hlist_for_each_entry_continue(tpos, pos, member) \
for (pos = (pos)->next; \
pos && ({ prefetch(pos->next); 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
pos = pos->next)
/**
* define hlist_for_each_entry_from - Iterate continuing from an existing point
* @tpos: the type * to use as a loop counter.
* @pos: the &struct hlist_node to use as a loop counter.
* @member: the name of the hlist_node within the struct.
*
* Iterate over an hlist continuing from an existing point
*/
#define hlist_for_each_entry_from(tpos, pos, member) \
for (; pos && ({ prefetch(pos->next); 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; });\
pos = pos->next)
/**
* define hlist_for_each_entry_safe - Iterate an hlist safely
* @tpos: the type * to use as a loop counter.
* @pos: the &struct hlist_node to use as a loop counter.
* @n: another &struct hlist_node to use as temporary storage
* @head: the head for your list.
* @member: the name of the hlist_node within the struct.
*
* Iterate over an hlist of given type safe against removal of list entry
*/
#define hlist_for_each_entry_safe(tpos, pos, n, head, member) \
for (pos = (head)->first; \
pos && ({ n = pos->next; 1; }) && \
({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
pos = n)
/**
* define list_for_each_prev - Iterate over a list in reverse order
* @pos: the &struct list_head to use as a loop counter.
* @head: the head for your list.
*/
#define list_for_each_prev(pos, head) \
for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
pos = pos->prev, prefetch(pos->prev))
/**
* define list_for_each_entry - Iterate over a list of given type
* @pos: the type * to use as a loop counter.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry(pos, head, member) \
for (pos = list_first_entry((head), typeof(*pos), member), \
prefetch(pos->member.next); \
&pos->member != (head); \
pos = list_entry(pos->member.next, typeof(*pos), member), \
prefetch(pos->member.next))
/**
* define list_for_each_entry_reverse - Iterate backwards over a list
* @pos: the type * to use as a loop counter.
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*
* Iterate backwards over a list of given type.
*/
#define list_for_each_entry_reverse(pos, head, member) \
for (pos = list_entry((head)->prev, typeof(*pos), member); \
prefetch(pos->member.prev), &pos->member != (head); \
pos = list_entry(pos->member.prev, typeof(*pos), member))
/**
* define list_for_each_entry_safe - Iterate over a list of given type safe
* against removal of list entry
* @pos: the type * to use as a loop counter.
* @n: another type * to use as temporary storage
* @head: the head for your list.
* @member: the name of the list_struct within the struct.
*/
#define list_for_each_entry_safe(pos, n, head, member) \
for (pos = list_first_entry((head), 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))
/**
* define list_for_each_entry_safe_reverse - Iterate backwards over a list of
* given type safely against removal
* of entry
* @pos: the type * to use as a loop counter.
* @n: another type * to use as temporary storage
* @head: the head for your list.
* @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))
#endif /* __LIBCFS_UTIL_LIST_H__ */
