contain_of 浅析

关于container_of见kernel.h中:
/**
* container_of - cast a member of a structure out to the containing structure
* @ptr:     the pointer to the member.
* @type:     the type of the container struct this is embedded in.
* @member:     the name of the member within the struct.
*
*/
#define container_of(ptr, type, member) ({             /
         const typeof( ((type *)0)->member ) *__mptr = (ptr);     /
         (type *)( (char *)__mptr - offsetof(type,member) );})
container_of在Linux Kernel中的应用非常广泛,它用于获得某结构中某成员的入口地址.

#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
TYPE是某struct的类型 0是一个假想TYPE类型struct,MEMBER是该struct中的一个成员. 由于该struct的基地址为0, MEMBER的地址就是该成员相对与struct头地址的偏移量.

 

 

原文摘自：http://blog.csdn.net/yinkaizhong/article/details/4093795