openwrt使用list

openwrt中用到双向无头链表，实际应用时应在外部定义实体链表头，后续可直接应用链表函数（宏定义已将链表头排除在外）：

static struct list_head timeouts = LIST_HEAD_INIT(timeouts);
static struct list_head processes = LIST_HEAD_INIT(processes);

与linux相同，定义如下：

#ifndef _LINUX_LIST_H_
#define _LINUX_LIST_H_

#include <stddef.h>
#include <stdbool.h>

#define  prefetch(x)

#ifndef container_of
#define container_of(ptr, type, member) \
    ({ \
        const typeof(((type *)NULL)->member) *__mptr = (ptr); \
        (type *)((char *)__mptr - offsetof(type, member)); \
    })
#endif

struct list_head {
    struct list_head *next;
    struct list_head *prev;
};

初始化

#define LIST_HEAD_INIT(name) {&(name), &(name)}
#undef LIST_HEAD
#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->prev = list;
}

list属性

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

static inline bool
list_is_first(const struct list_head *list,
    const struct list_head *head)
{
    return (list->prev == head);
}

static inline bool
list_is_last(const struct list_head *list,
    const struct list_head *head)
{
    return (list->next == head);
}

list常用操作--增add

static inline void
_list_add(struct list_head *_new, struct list_head *prev,
    struct list_head *next)
{
    prev->next = _new;
    _new->prev = prev;
    _new->next = next;
    next->prev = _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);
}

list常用操作--删del

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

static inline void
list_del(struct list_head *entry)
{
    _list_del(entry);
    entry->next = entry->prev = NULL;
}

static inline void
list_del_init(struct list_head *entry)
{
    _list_del(entry);
    INIT_LIST_HEAD(entry);
}

list常用操作--改move

static inline void
list_move(struct list_head *list, struct list_head * head)
{
    _list_del(list);
    list_add(list, head);
}

static inline void
list_move_tail(struct list_head *list, struct list_head *head)
{
    _list_del(list);
    list_add_tail(list, head);
}

list常用操作--查

#define list_entry(ptr, type, field) container_of(ptr, type, field)
#define list_first_entry(ptr, type, field) list_entry((ptr)->next, type, field)
#define list_last_entry(ptr, type, field) list_entry((ptr)->prev, type, field)

#define list_for_each(p, head) \
    for(p=(head)->next; p!=(head); p=p->next)

#define list_for_each_safe(p, n, head) \
    for(p = (head)->next, n=p->next; p!= (head); p=n, n=p->next)

#define list_for_each_entry(p, h, field) \
    for(p = list_first_entry(h, typeof(*p), field); \
        &p->field != (h); \
        p = list_entry(p->field.next, typeof(*p), field))

#define list_for_each_entry_safe(p, n, h, field) \
    for(p = list_first_entry(h, typeof(*p), field), \
        n = list_entry(p->field.next, typeof(*p), field); \
        &p->field != (h); \
        p = n, n = list_entry(n->field.next, typeof(*p), field))

#define list_for_each_entry_reverse(p, h, field) \
    for(p = list_last_entry(h, typeof(*p), field); \
        &p->field != (h); \
        p = list_entry(p->field.prev, typeof(*p), field))

#define list_for_each_prev(p, h) \
    for(p = (h)->prev; p != (h); p = p->prev)

#define list_for_each_prev_safe(p, n, h) \
    for(p = (h)->prev, n = p->prev; p != (h); \
        p = n, n = p->prev)

list常用操作--拼接splice

static inline void
_list_splice(const struct list_head *list, struct list_head *prev, struct list_head *next)
{
    struct list_head *first, last;

    if(list_empty(list))
        return ;

    first = list->next;
    last = list->prev;
    first->prev = prev;
    prev->next = first;
    last->next = next;
    next->prev = last;
}

static inline void
list_splice(const struct list_head *list, struct list_head *head)
{
    _list_splice(list, head, head->next);
}

static inline void
list_splice_tail(struct list_head *list, struct list_head *head)
{
    _list_splice(list, head->prev, head);
}

static inline void
list_splice_init(struct list_head *list, struct list_head *head)
{
    _list_splice(list, head, head->next);
    INIT_LIST_HEAD(list);
}
static inline void
list_splice_tail_init(struct list_head *list, struct list_head *head)
{
    _list_splice(list, head->prev, head);
    INIT_LIST_HEAD(list);
}

#endif

摘自：libubox