svn commit: r243215 - user/andre/tcp_workqueue/sys/sys

[Andre Oppermann]

On 19.11.2012 18:01, mdf at FreeBSD.org wrote:
> On Mon, Nov 19, 2012 at 5:33 AM, Andre Oppermann <andre at freebsd.org> wrote:
>> On 19.11.2012 12:45, Gleb Smirnoff wrote:
>>>
>>> On Sun, Nov 18, 2012 at 12:17:07PM +0000, Andre Oppermann wrote:
>>> A> Author: andre
>>> A> Date: Sun Nov 18 12:17:07 2012
>>> A> New Revision: 243215
>>> A> URL: http://svnweb.freebsd.org/changeset/base/243215
>>> A>
>>> A> Log:
>>> A>   Add mtodo(m, o, t) macro taking an additional offset into
>>> A>   the mbuf data section before the casting to type 't'.
>>>
>>> IMHO, argument order of (m, t, o) is more intuitive, since
>>> matches order of mtod().
>>
>>
>> Yes, but that looks rather horrible and counter-intuitive:
>>
>>   th = mtodo(m, struct tcphdr *, 20);
>>
>> vs.
>>
>>   th = mtodo(m, 20, struct tcphdr *);
>>
>> Reads m->m_data at offset 20 is struct tcphdr.
>>
>> Naming it mtood() wasn't convincing either. ;-)
>
> Why a cast at all?  Perpetuating the mistake of mtod()'s casting isn't
> necessary.  mtod() can't be fixed for source reasons, but the new one
> doesn't need to cast.  Since C automatically casts from void * to any
> other pointer, the code gets shorter (usually) too:
>
> th = mtodo(m, 20);

m->m_data is caddr_t which is "char *"

> Not that I care much, it's just if we're having a bikeshed I have my
> favorite colors. :-)

-- 
Andre