6.下面的代码是 linux kernel的代码，请指出其中的错误来： struct student{ int id; char name[20]; struct list_head 1ist; }; static LIST_HEAD(student_list); static DEFINE MUTEX(student_mutex); static int add_student(struct student *stu) { struct student *new_stu = NULL; if(!stu) { printk(KERN_ ERR " Invalid argument\n"); return -EINVAL; } if (stu->id <= 0){ i printk(KERN_ ERR "Invalid id\n"); return -EINVAL; } if(!mutex_trylock(&student_mutex)){ printk(KERN_ INFO "Failed to lock mutex\n"); return-EBUSY; } new_stu = kmalloc(sizeof(struct student), GFP KERNEL); if(!new_ stu) { printk(KERN ERR "Failed to allocate memory\n"); return -ENOMEM; *new_stu= *stu; list_add_ tail(&new_stu->list, &student_list); printk(KERN_ INFO "Added student: id=%d, name-%s\n", stu->id, stu->name); mutex_unlock(&student_mutex); return 0; }

这段代码存在以下几个错误：

1. 在定义结构体 student 中，list_head 的名称中包含数字 1，请修改为合法的名称。

2. DEFINE MUTEX 应该改为 DEFINE_MUTEX。

3. if (stu->id <= 0){ i 应该改为 if (stu->id <= 0){

4. kmalloc 中 GFP KERNEL 应该改为 GFP_KERNEL。

修改后的代码如下：

struct student{
    int id;
    char name[20];
    struct list_head list;
};

static LIST_HEAD(student_list);
static DEFINE_MUTEX(student_mutex);

static int add_student(struct student *stu) {
    struct student *new_stu = NULL;

    if (!stu) {
        printk(KERN_ERR "Invalid argument\n");
        return -EINVAL;
    }

    if (stu->id <= 0) {
        printk(KERN_ERR "Invalid id\n");
        return -EINVAL;
    }

    if (!mutex_trylock(&student_mutex)) {
        printk(KERN_INFO "Failed to lock mutex\n");
        return -EBUSY;
    }

    new_stu = kmalloc(sizeof(struct student), GFP_KERNEL);

    if (!new_stu) {
        printk(KERN_ERR "Failed to allocate memory\n");
        return -ENOMEM;
    }

    *new_stu = *stu;
    list_add_tail(&new_stu->list, &student_list);
    printk(KERN_INFO "Added student: id=%d, name=%s\n", stu->id, stu->name);
    mutex_unlock(&student_mutex);
    return 0;
}