Messages in this thread | | | From | (Linus Torvalds) | Subject | Re: PATCH: type safe(r) list_entry repacement: generic_out_cast | Date | Wed, 24 Jul 2002 01:04:53 +0000 (UTC) |
| |
In article <200207240051.CAA16434@harpo.it.uu.se>, Mikael Pettersson <mikpe@csd.uu.se> wrote: >On Tue, 23 Jul 2002 18:58:52 -0400, Kevin O'Connor wrote: >>#define BackPtr(ptr, type, member) ({ \ >> typeof( ((type *)0)->member ) *__mptr = (ptr); \ >> ((type *)( (char *)__mptr - (unsigned long)(&((type *)0)->member) ));}) > >I've seen this sort of code several times now in the Linux kernel, >and I've never liked it. Is there some reason why you guys avoid >offsetof() like the plague?
Trivial answer: offsetof() does not exist when you don't have system header files.
So it's not that it's getting avoided, it _has_ to be re-implemented anyway. And once you do that, you might as well do it right (ie what the kernel wants is not offsetof, but a new pointer.
Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |