mbuf changes

Rui Paulo rpaulo at freebsd.org
Sat Oct 2 23:29:25 UTC 2010

On 2 Oct 2010, at 21:35, Juli Mallett wrote:

> On Sat, Oct 2, 2010 at 12:07, Rui Paulo <rpaulo at freebsd.org> wrote:
>> On 2 Oct 2010, at 16:29, Robert Watson wrote:
>>> On Thu, 30 Sep 2010, Julian Elischer wrote:
>>>> On 9/30/10 10:49 AM, Ryan Stone wrote:
>>>>> It's not a big thing but it would be nice to replace the m_next and m_nextpkt fields with queue.h macros.
>>>> funny, I've never even thought of that..
>>> I have, and it's a massive change touching code all over the kernel in vast quantities.  While in principle it's a good idea (consistently avoid hand-crafted linked lists), it's something I'd discourage on the basis that it probably won't significant reduce the kernel bug count, but will make it even harder for vendors with large local changes to the network stack to keep up.
>> I think it could also increase the kernel bug count. Unfortunately, we can't do this incrementally.
> Can't we?  What about a union, so that we can gradually convert things
> but keep ABI and API compatibility?  I mean, as long as we use the
> right queue.h type, anyway, it should be consistent?  STAILQ,
> presumably.

Well, I don't have the layout of the mbuf struct offhand, but it's an idea worth investigating.

Rui Paulo

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