container_of

#include
#include

#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})

struct Substru
{
       int val;
};
          
struct Stru
{
       int val;
       struct Substru sub;
};

int main()
{
    struct Stru ptr;
    container_of(&ptr.sub, struct Stru, sub);
   
    printf("%x %x %x\n", container_of(&ptr.sub, struct Stru, sub), &ptr, &ptr.sub);
   
    while(1);
    return 0;
}
运行结果：