1 /*****************************
2 * container_of - cast a member of a structure out to the containing structure 功能：通过结构体成员找到成员所属结构体的首地址
3 * @ptr: the pointer to the member.
4 * @type: the type of the container struct this is embedded in.
5 * @member: the name of the member within the struct.
6 *
7 ************************************/
8 #define container_of(ptr, type, member) ({ \
9 const typeof(((type *)
0)->member) * __mptr =
(ptr); \
10 (type *)((
char *)__mptr - offsetof(type, member)); })
typeof(((type *)0)->member) * __mptr = (ptr);定义了一个type*类型的结构体子成员_mptr，并将ptr赋给它。（注：((type *）0)获得的是type的首地址）
(type *)((char *)__mptr - offsetof(type, member)); #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)；offsetof函数实现计算member相对于结构体type的偏移。然后通过_mptr与其相减，即可获得mptr成员所属结构体的首地址。
转载于:https://www.cnblogs.com/embeded-linux/p/10828169.html
