在linux内核中有这么一个宏定义,使用非常频繁。
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/**
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* list_entry - get the struct for this entry
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* @ptr: the &struct list_head pointer.
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* @type: the type of the struct this is embedded in.
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* @member: the name of the list_struct within the struct.
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*/
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#define list_entry(ptr, type, member) \
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container_of(ptr, type, member)
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/**
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* container_of - cast a member of a structure out to the containing structure
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*
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* @ptr: the pointer to the member.
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* @type: the type of the container struct this is embedded in.
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* @member: the name of the member within the struct.
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*
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*/
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#define container_of(ptr, type, member) ({ \
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const typeof( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)( (char *)__mptr - offsetof(type,member) );})
下面给出一个例子的示意图,方便理解
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