On Fri, Mar 09, 2012 at 11:51:54PM +0530, Vijay Chauhan wrote:
> Hi,
>
> I'm checking the container_of and offsetof macro
>
> #define container_of(ptr, type, member) ({ \
> const typeof( ((type *)0)->member ) *__mptr = (ptr);
> (type *)( (char *)__mptr - offsetof(type,member) );})
>
> #define offsetof(TYPE, MEMBER) \
> ((size_t) &((TYPE *)0)->MEMBER)
>
>
> I did not understand the first line of both macro. Will it not create
> the NULL pointer dereference problem? I know it works and read some
> article but it did not explain this part, so can anyone explain why
> the NULL pointer error is not coming. Am I missing something?
> Any C language specification of such example.
Did you see this:
http://www.kroah.com/log/linux/container_of.html
after reading that, if you have further questions, please let us know.
greg k-h
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