RX checksum offloading problem
Yonghyeon PYUN
pyunyh at gmail.com
Tue May 13 05:21:39 UTC 2014
On Mon, May 12, 2014 at 01:22:03PM +0200, Michael Tuexen wrote:
> On 12 May 2014, at 03:36, Yonghyeon PYUN <pyunyh at gmail.com> wrote:
>
> > On Fri, May 09, 2014 at 12:46:48PM +0200, Michael Tuexen wrote:
> >> On 09 May 2014, at 03:35, Yonghyeon PYUN <pyunyh at gmail.com> wrote:
> >>
[...]
> > Oops, sorry. You're right. Probably I was confused with old memory
> > when I worked on that area. I've quickly read IP reassembly code
> > again and as you said, it should work. However it seems there is a
> > checksumming bug here.
> >
> > /*
> > * In order to do checksumming faster we do 'end-around carry' here
> > * (and not in for{} loop), though it implies we are not going to
> > * reassemble more than 64k fragments.
> > */
> > m->m_pkthdr.csum_data =
> > (m->m_pkthdr.csum_data & 0xffff) + (m->m_pkthdr.csum_data >> 16);
> >
> > I guess the line above didn't account possible carry happened after
> > the computation. Probably it could be rewritten as the following.
> >
> > while (m->m_pkthdr.csum_data & 0xffff0000)
> > m->m_pkthdr.csum_data = (m->m_pkthdr.csum_data & 0xffff) +
> > (m->m_pkthdr.csum_data >> 16);
> I think you are right here. Good catch. Will you fix it?
>
Done in r265942.
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