I have a question about the macro " container_of(ptr, type, member) "
I can write it as this,
#define container_of(ptr, type, member) ({ \
(type *) ((char *) ptr - offset_of(type, member)); \
})
It can act the same as
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
So why we don't use the first one ?
Thanks for your answer.
(I am a kernel newbie ,and sorry for my poor english~)