ARM network trouble after recent mbuf changes

[Zbyszek Bodek]

On 27.08.2013 13:05, Andre Oppermann wrote:
> On 27.08.2013 11:38, Michael Tuexen wrote:
>> On Aug 27, 2013, at 8:53 AM, Andre Oppermann <andre at FreeBSD.org> wrote:
>>
>>> On 27.08.2013 00:22, Thomas Skibo wrote:
>>>> On 8/26/13 2:11 PM, Andre Oppermann wrote:
>>>>>
>>>>> Can you try this patch see check if it makes a difference on the
>>>>> bitfield?
>>>>
>>>> Actually, this works for me.  But, I'm worried that somewhere else
>>>> something is going to trip over a
>>>> struct pkthdr not being 64-bit aligned.  There are several 64-bit
>>>> fields in there.
>>>
>>> The problem is the disconnect between the definition of MLEN and
>>> MHLEN and
>>> the effective size/padding of struct mbuf.  That's the true bug.
>>>
>>> On LP64 all is fine.  On i386 it turns out to be fine too because
>>> doesn't
>>> care.
>>>
>>> MLEN and MHLEN are incorrectly derived.  In fact they should be
>>> derived from
>>> stuct mbuf where this padding would be taking into account.  However
>>> the way
>>> it is structured right now it that would create a circular dependency.
>>>
>>> Please try the patch below to confirm.  If it fixes your problem for now
>>> I'm going to commit as an immediate fix while searching for a better
>>> long
>>> term stable solution.
>>>
>>> -- 
>>> Andre
>>>
>>> Index: sys/mbuf.h
>>> ===================================================================
>>> --- sys/mbuf.h  (revision 254953)
>>> +++ sys/mbuf.h  (working copy)
>>> @@ -94,6 +94,9 @@
>>>         int32_t          mh_len;        /* amount of data in this
>>> mbuf */
>>>         uint32_t         mh_type:8,     /* type of data in this mbuf */
>>>                          mh_flags:24;   /* flags; see below */
>>> +#if defined(__ILP32__)
>>> +       uint32_t         mh_pad;        /* pad to 64 bit alignment */
>>> +#endif
>>> };
>>
>> OK. It doesn't work. The reason is, that __ILP32__ is not defined... At
>> lease I don't see it anywhere in the BSD stack. So I'm currently
>> rebuilding
>> with #if !defined(__LP64__) instead. I'll let you know...
> 
> Thanks.  I've changed the test accordingly.
> 
> While doing the CTASSERTs to prevent such an incident in the future I
> stumbled
> across a bit of evil name space pollution in mbuf.h.  It is impossible
> to take
> sizeof(struct m_ext) because "m_ext" is redefined to point into struct
> mbuf.
> 
> In addition to the alignment fix I've solved the namespace issues with
> m_ext
> and the stupidly named struct pkthdr as well and properly prefixed
> them.  The
> fallout from LINT was zero (as it should be).
> 
>  http://people.freebsd.org/~andre/m_hdr-alignment-20130827.diff
> 
> Please test.
> 

Hello Andre.

Works for me.

Best regards
Zbyszek Bodek