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SubjectRe: container-of Implementation
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On Mon, Jan 14, 2013 at 11:46 AM, Schrober <franzschrober@yahoo.de> wrote:
> I wondered why the container_of implementation is so complicated.
>
> #define container_of(ptr, type, member) ({ \
> const typeof( ((type *)0)->member ) *__mptr = (ptr); \
> (type *)( (char *)__mptr - offsetof(type,member) );})
>
> isn't the __mptr not unnecessary? Why not following version?
>
> #define container_of(ptr, type, member) \
> ((type *)((char *)(ptr) - offsetof(type, member)))

The __mptr construct will cause a compiler warning if ptr is of the
wrong type.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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