list.h

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#ifndef __LINUX_LIST_H__
#define __LINUX_LIST_H__

/*
 * 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 LIST_HEAD(name) \
    struct list_head name = LIST_HEAD_INIT(name)

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

/*
 * 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;
}

static inline void list_add(struct list_head *new, struct list_head *head)
{
    __list_add(new, head, head->next);
}

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;
}

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

static inline void list_del_init(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    INIT_LIST_HEAD(entry);
}

static inline void list_move(struct list_head *list, struct list_head *head)
{
    __list_del(list->prev, list->next);
    list_add(list, head);
}

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);
}

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

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;
}

static inline void list_splice(struct list_head *list, struct list_head *head)
{
    if (!list_empty(list))
        __list_splice(list, head);
}

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(ptr, type, member) \
    ((type *)((char *)(ptr)-(char *)(&((type *)0)->member)))

#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(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
        pos = n, n = pos->next)

#ifndef list_for_each_prev

#define list_for_each_prev(pos, head) \
    for (pos = (head)->prev, prefetch(pos->prev); pos != (head); \
        pos = pos->prev, prefetch(pos->prev))

#endif /* list_for_each_prev */

#ifndef list_for_each_entry

#define list_for_each_entry(pos, head, type, member)        \
        for (pos = list_entry((head)->next, type, member),  \
             prefetch(pos->member.next);            \
         &pos->member != (head);                    \
         pos = list_entry(pos->member.next, type, member),  \
         prefetch(pos->member.next))
#endif /* list_for_each_entry */

#ifndef list_for_each_entry_safe

#define list_for_each_entry_safe(pos, n, head, type, member)            \
        for (pos = list_entry((head)->next, type, member),  \
        n = list_entry(pos->member.next, type, member); \
         &pos->member != (head);                    \
         pos = n, n = list_entry(n->member.next, type, member))
#endif /* list_for_each_entry_safe */

#endif /* __LINUX_LIST_H__ */