Rev.2を表示中。最新版はこちら。

list_for_each_entryは以下の様に展開されて、ちょっと引いてしまいそうですが、リスト処理でlist_for_eachとlist_entryの機能をもたせたものです。

#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))

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

#define list_entry(ptr, type, member) \
       container_of(ptr, type, member)

以下は、list_for_each_entryとlist_for_eachでリストを走査するサンプルです。

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/slab.h>

MODULE_DESCRIPTION("list_for_each_entry");
MODULE_AUTHOR("y.kitamura");

static LIST_HEAD(head);

struct my_object {
    struct list_head list;
    int sec;
};

void    set_data(void)
{
    struct my_object *myobj;
    int i;

    for (i = 0; i < 10; ++i) {
        myobj = (struct my_object*)kmalloc(sizeof(struct my_object), GFP_KERNEL);
        myobj->sec = i;
        list_add_tail(&myobj->list, &head);
    }
}

void    for_each(void)
{
    struct list_head *p;
    struct my_object *myobj;

    list_for_each(p, &head) {
        myobj = list_entry(p, struct my_object, list);
        printk("%d:", myobj->sec);
    }
    printk("\n");
}

void    for_each_entry(void)
{
    struct my_object *myobj;
    list_for_each_entry(myobj, &head, list) {
        printk("%d:", myobj->sec);
    }
    printk("\n");
}

int init_module(void)
{
    set_data();
    for_each();
    for_each_entry();
    return 0;
}

void cleanup_module(void)
{
    struct my_object *myobj;
    while(!list_empty(&head)) {
        myobj = list_entry(head.next, struct my_object, list);
        list_del(&myobj->list);
        kfree(myobj);
    }
}

[root@localhost lkm]# insmod list_head.ko
[root@localhost lkm]# dmesg
  :
  :
[11090.009091] pcnet32 0000:02:01.0: eth0: link up
[11092.004380] pcnet32 0000:02:01.0: eth0: link down
[11102.008055] pcnet32 0000:02:01.0: eth0: link up
[21452.459410] 0:1:2:3:4:5:6:7:8:9:
[21452.459423] 0:1:2:3:4:5:6:7:8:9: