include/linux/list.h

/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */

#ifndef __LINUX_LIST_H
#define __LINUX_LIST_H

#include <linux/types.h>

#define LIST_HEAD_INIT(name) { &(name), &(name) }
#define LIST_HEAD(name) \
        struct list_head name = LIST_HEAD_INIT(name)

#define POISON_POINTER_DELTA 0
#define LIST_POISON1  ((void *) 0x100 + POISON_POINTER_DELTA)
#define LIST_POISON2  ((void *) 0x200 + POISON_POINTER_DELTA)


static inline void INIT_LIST_HEAD(struct list_head *list)
{
        list->next = list;
        list->prev = list;
}

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 - 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;
        prev->next = 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_entry(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
}

static inline void list_del(struct list_head *entry)
{
        __list_del(entry->prev, entry->next);
        entry->next = LIST_POISON1;
        entry->prev = LIST_POISON2;
}

static inline int list_empty(const struct list_head *head)
{
	return head->next == head;
}

#define list_entry(ptr, type, member) \
        container_of(ptr, type, member)
#define list_first_entry(ptr, type, member) \
        list_entry((ptr)->next, type, member)
#define list_last_entry(ptr, type, member) \
        list_entry((ptr)->prev, type, member)
#define list_next_entry(pos, member) \
        list_entry((pos)->member.next, typeof(*(pos)), member)
#define list_prev_entry(pos, member) \
        list_entry((pos)->member.prev, typeof(*(pos)), member)
#define list_for_each_entry(pos, head, member) \
	for (pos = list_first_entry(head, typeof(*pos), member); \
	     &pos->member != (head); \
	     pos = list_next_entry(pos, member))
#define list_for_each_entry_from(pos, head, member) \
	for (; &pos->member != (head); \
	     pos = list_next_entry(pos, member))
#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); \
	     &pos->member != (head); \
	     pos = n, n = list_next_entry(n, member))

#endif