技術標籤：Linux 核心連結串列核心

0x01:連結串列
連結串列是Linux核心中非常重要的資料結構，在日常核心驅動開發過程中，往往需要遍歷核心的某個連結串列，核心提供了一套完整的雙鏈表機制，使開發者可以在核心私有資料結構中輕鬆構建雙向連結串列，這裡一起學習以下雙向連結串列的構建和遍歷方法，具體連結串列的知識可以參考文末連結；

0x02:雙向連結串列的構建和遍歷
直接給出程式碼：

//list.c
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>

/* header of list */
 

#include <linux/list.h>

/* private structure */
struct node {
    const char *name;
    struct list_head list;
};

/* Initialize a group node structure */
static struct node node0 = { .name = "BiscuitOS_node0", };
static struct node node1 = { .name = "BiscuitOS_node1", };
static
 
 struct node node2 = { .name = "BiscuitOS_node2", };
static struct node node3 = { .name = "BiscuitOS_node3", };
static struct node node4 = { .name = "BiscuitOS_node4", };
static struct node node5 = { .name = "BiscuitOS_node5", };
static struct node node6 = { .
 
name = "BiscuitOS_node6", };

/* Declaration and implement a bindirect-list */
LIST_HEAD(BiscuitOS_list);

static __init int list_entry_init(void)
{
  struct node *np;

  /* add a new entry on special entry */
  list_add_tail(&node0.list, &BiscuitOS_list);
  list_add_tail(&node1.list, &BiscuitOS_list);
  list_add_tail(&node2.list, &BiscuitOS_list);
  list_add_tail(&node3.list, &BiscuitOS_list);
  list_add_tail(&node4.list, &BiscuitOS_list);
  list_add_tail(&node5.list, &BiscuitOS_list);
  list_add_tail(&node6.list, &BiscuitOS_list);

  printk("BiscuitOS_list:\n");
  /* Traverser all node on bindirect-list */
  list_for_each_entry(np, &BiscuitOS_list, list)
    printk("%s\n", np->name);

  /* get the struct for this entry */
  np = list_entry(BiscuitOS_list.next, struct node, list);
  printk("The entry struct node: %s\n", np->name);

  /* get the first element from a list */
  np = list_first_entry(&BiscuitOS_list, struct node, list);
  printk("The first entry struct node: %s\n", np->name);

  return -1;
}


static void __exit list_entry_exit(void)
{
  printk("Bye bye list_entry\n");
}

module_init(list_entry_init);
module_exit(list_entry_exit); 
MODULE_LICENSE("GPL");

Makefile:

obj-m += list.o

KBUILD_CFLAGS+= -g

all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

0x03:實際效果

[ 2113.170373] BiscuitOS_list:
[ 2113.170374] BiscuitOS_node0
[ 2113.170374] BiscuitOS_node1
[ 2113.170375] BiscuitOS_node2
[ 2113.170375] BiscuitOS_node3
[ 2113.170375] BiscuitOS_node4
[ 2113.170375] BiscuitOS_node5
[ 2113.170375] BiscuitOS_node6
[ 2113.170376] The entry struct node: BiscuitOS_node0
[ 2113.170376] The first entry struct node: BiscuitOS_node0

0x04:程式碼分析
主要程式碼邏輯為：
1.建立私有資料結構體 struct node;
2.初始化資料結構;
3.宣告連結串列頭，用於後續資料訪問;
4.list_for_each_entry()函式遍歷雙向連結串列，引數1為私有資料結構型別，引數2為頭節點，引數3為struct node list_head;

參考連結：
https://biscuitos.github.io/blog/LIST/