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/* 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);
}
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