我有不懂了，我好像用不到**p，为啥就不能*p

#include<stdio.h>
#include<stdlib.h>
struct jiedian
{
int dat ;struct jiedian*next;
};
//头插法
void biao(struct jiedian **p,int x)//&p
{while (x!=1)
{
struct jiedian *a;
a=(struct jiedian*)malloc(sizeof(struct jiedian));a->next=*p;undefined
*p=a;
}
}
int main(){
int x;
struct jiedian *y;
struct jiedian kong;
y=&kong;
biao(&y,x);
}
错误代码我上完课回宿舍发出来