svn commit: r258328 - head/sys/net

[Julian Elischer]

On 11/20/13, 2:02 PM, Adrian Chadd wrote:
> Can we revert this and just quickly put together something else that
> won't potentially come back to bite us with weird side effects?
>
> My suggestions (and I'm happy to do this work if needed):
>
> * create a lightweight mbuf queue representation so an mbuf list isn't
> just the mbuf header pointer;
> * create a new ether input (say, ether_input_multi) that takes an mbuf
> list, so existing driver code does the right thing.
>
> After that it'd be nice to write a set of mbuf list macros for
> abstract the whole queue, dequeue, concat, iterate, etc (like
> sys/queue.h, but for mbufs.)
>
> What do people think?
>
> (I've been doing it for m->next chained things, but not m->m_nextpkt things..)

I was thinking:
new interfaces.. (your -multi names sound good).
macros for handling said lists so that people don't screw them up
Old drivers run with no change.

>
>
>
> -adrian
>
>
> On 18 November 2013 14:58, George V. Neville-Neil <gnn at freebsd.org> wrote:
>> Author: gnn
>> Date: Mon Nov 18 22:58:14 2013
>> New Revision: 258328
>> URL: http://svnweb.freebsd.org/changeset/base/258328
>>
>> Log:
>>    Allow ethernet drivers to pass in packets connected via the nextpkt pointer.
>>    Handling packets in this way allows drivers to amortize work during packet reception.
>>
>>    Submitted by: Vijay Singh
>>    Sponsored by: NetApp
>>
>> Modified:
>>    head/sys/net/if_ethersubr.c
>>
>> Modified: head/sys/net/if_ethersubr.c
>> ==============================================================================
>> --- head/sys/net/if_ethersubr.c Mon Nov 18 22:55:50 2013        (r258327)
>> +++ head/sys/net/if_ethersubr.c Mon Nov 18 22:58:14 2013        (r258328)
>> @@ -708,13 +708,25 @@ static void
>>   ether_input(struct ifnet *ifp, struct mbuf *m)
>>   {
>>
>> +       struct mbuf *mn;
>> +
>>          /*
>> -        * We will rely on rcvif being set properly in the deferred context,
>> -        * so assert it is correct here.
>> +        * The drivers are allowed to pass in a chain of packets linked with
>> +        * m_nextpkt. We split them up into separate packets here and pass
>> +        * them up. This allows the drivers to amortize the receive lock.
>>           */
>> -       KASSERT(m->m_pkthdr.rcvif == ifp, ("%s: ifnet mismatch", __func__));
>> +       while (m) {
>> +               mn = m->m_nextpkt;
>> +               m->m_nextpkt = NULL;
>>
>> -       netisr_dispatch(NETISR_ETHER, m);
>> +               /*
>> +                * We will rely on rcvif being set properly in the deferred context,
>> +                * so assert it is correct here.
>> +                */
>> +               KASSERT(m->m_pkthdr.rcvif == ifp, ("%s: ifnet mismatch", __func__));
>> +               netisr_dispatch(NETISR_ETHER, m);
>> +               m = mn;
>> +       }
>>   }
>>
>>   /*