下面的代码是linux kernel的代码，请指出其中的错误,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; }

代码中有两个错误：

1. 在第10行中，printk函数的字符串缺少一个双引号，应为："Invalid argument\n"。

2. 在第17行中，mutex-trylock函数应为mutex_trylock函数，即函数名中的"-"应该改为"_"。

正确的代码如下：

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;
}