Question

我正在从事一个练习项目并且遇到了麻烦。我试图编写一个简单的内核模块，创建几个生日记录并将其值打印到内核日志缓冲区。我很难搞清楚如何将字符串值分配给记录中的char指针。这是我的代码：

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

struct birthday{
    int day;
    int month;
    int year;
    char *name;
    struct list_head list;
};
static LIST_HEAD(birthday_list);

/*this fn is called when the module is loaded*/
int simple_init(void){
    struct birthday *ptr;
    struct birthday *person;
    person = kmalloc(sizeof(*person), GFP_KERNEL);
    person->day=22;
    person->month=7;
    person->year=1990;
    strcpy(person->name, "Jane");

    struct birthday *person2;
    person2 = kmalloc(sizeof(*person2), GFP_KERNEL);
    person2->day=4;
    person2->month=3;
    person2->year=1990;
    strcpy(person->name, "Michael");

    struct birthday *person3;
    person3 = kmalloc(sizeof(*person3), GFP_KERNEL);
    person3->day=4;
    person3->month=3;
    person3->year=1990;
    strcpy(person->name, "Tom");

    struct birthday *person4;
    person4 = kmalloc(sizeof(*person4), GFP_KERNEL);
    person4->day=4;
    person4->month=4;
    person4->year=1990;
    strcpy(person->name, "Lacey");

    struct birthday *person5;
    person5 = kmalloc(sizeof(*person5), GFP_KERNEL);
    person5->day=4;
    person5->month=5;
    person5->year=1990;
    strcpy(person->name, "Ruth");


    INIT_LIST_HEAD(&person->list);
    list_add_tail(&person->list, &birthday_list);
    list_add_tail(&person2->list, &birthday_list);
    list_add_tail(&person3->list, &birthday_list);
    list_add_tail(&person4->list, &birthday_list);
    list_add_tail(&person5->list, &birthday_list);

    printk(KERN_INFO "Module initialized");
    list_for_each_entry(ptr,&birthday_list, list){
        printk(KERN_INFO "Name: %s, Birthday: %d/%d/%d\n",ptr->name,ptr->month,ptr->day,ptr->year);
    }
    return 0;
}

/*this fn is called when the module is removed*/
void simple_exit(void){
    struct birthday *ptr, *next;

    list_for_each_entry_safe(ptr, next, &birthday_list, list){
        list_del(&ptr->list);
        kfree(ptr);
    }

    printk(KERN_INFO "Removing module\n");
}
/*macros for registering module entrance and exit points*/
module_init(simple_init);
module_exit(simple_exit);

当我摆脱字符串属性以及与之关联的所有指令时，代码会编译并运行。原样，代码编译但当我运行它时系统冻结。谢谢大家！

Answer 1

我找到了解决方案。在进行赋值之前，我忘了将内核空间分配给我的字符串。这是更正的代码，现在可以使用。

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

struct birthday{
    int day;
    int month;
    int year;
    char* name;
    struct list_head list;
};
static LIST_HEAD(birthday_list);

/*this fn is called when the module is loaded*/
int simple_init(void){
    struct birthday *ptr;
    struct birthday *person,*person2,*person3,*person4,*person5;
    person = kmalloc(sizeof(*person), GFP_KERNEL);
    person->day=22;
    person->month=7;
    person->year=1990;
    person->name=kmalloc(sizeof("Jane")+1, GFP_KERNEL);
    strcpy(person->name, "Jane");

    person2 = kmalloc(sizeof(*person2), GFP_KERNEL);
    person2->day=4;
    person2->month=3;
    person2->year=1990;
    person2->name=kmalloc(sizeof("Michael")+1, GFP_KERNEL);
    strcpy(person2->name, "Michael");

    person3 = kmalloc(sizeof(*person3), GFP_KERNEL);
    person3->day=4;
    person3->month=3;
    person3->year=1990;
    person3->name=kmalloc(sizeof("Lacey")+1, GFP_KERNEL);
    strcpy(person3->name, "Lacey");

    person4 = kmalloc(sizeof(*person4), GFP_KERNEL);
    person4->day=4;
    person4->month=4;
    person4->year=1990;
    person4->name=kmalloc(sizeof("Tom")+1, GFP_KERNEL);
    strcpy(person4->name, "Tom");

    person5 = kmalloc(sizeof(*person5), GFP_KERNEL);
    person5->day=4;
    person5->month=5;
    person5->year=1990;
    person5->name=kmalloc(sizeof("Stuart")+1, GFP_KERNEL);
    strcpy(person5->name, "Stuart");


    INIT_LIST_HEAD(&person->list);
    list_add_tail(&person->list, &birthday_list);
    list_add_tail(&person2->list, &birthday_list);
    list_add_tail(&person3->list, &birthday_list);
    list_add_tail(&person4->list, &birthday_list);
    list_add_tail(&person5->list, &birthday_list);

    printk(KERN_INFO "Module initialized");
    list_for_each_entry(ptr,&birthday_list, list){
        printk(KERN_INFO "Name: %s, Birthday: %d/%d/%d\n",ptr->name,ptr->month,ptr->day,ptr->year);
    }
    return 0;
}

/*this fn is called when the module is removed*/
void simple_exit(void){
    struct birthday *ptr, *next;

    list_for_each_entry_safe(ptr, next, &birthday_list, list){
        list_del(&ptr->list);
        kfree(ptr);
    }

    printk(KERN_INFO "Removing module\n");
}
/*macros for registering module entrance and exit points*/
module_init(simple_init);
module_exit(simple_exit);

谢谢！

编写内核模块时，如何为字符串值指定char指针？

1 个答案: