Re: [dpdk-dev] [PATCH v2] net: prepare the outer ipv4 hdr for checksum

[Mohsin Kazmi <mohsin.kazmi14@gmail.com>]

Hi Olivier,

Thanks for the review.
Please find the comments inline below:

On Wed, Jun 30, 2021 at 3:09 PM Olivier Matz <olivier.matz@6wind.com> wrote:

> Hi Mohsin,
>
> Hope you are fine!
> Please see my comments below.
>
> On Wed, Jun 30, 2021 at 01:04:04PM +0200, Mohsin Kazmi wrote:
> > Re: [PATCH v2] net: prepare the outer ipv4 hdr for checksum
>
> I suggest to highlight that it this is the Intel-specific tx-prepare
> function in the commit title. What about:
>
  net: fix Intel-specific Tx preparation for outer checksums
>
> I'll update the commit title as suggested.

> Preparation the headers for the hardware offload
> > misses the outer ipv4 checksum offload.
> > It results in bad checksum computed by hardware NIC.
> >
> > This patch fixes the issue by setting the outer ipv4
> > checksum field to 0.
> >
> > Fixes: 4fb7e803eb1a ("ethdev: add Tx preparation")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Mohsin Kazmi <mohsin.kazmi14@gmail.com>
> > Acked-by: Qi Zhang <qi.z.zhang@intel.com>
> > ---
> >
> > v2:
> > * Update the commit message with Fixes.
> > ---
> >  lib/net/rte_net.h | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/net/rte_net.h b/lib/net/rte_net.h
> > index 434435ffa2..e47365099e 100644
> > --- a/lib/net/rte_net.h
> > +++ b/lib/net/rte_net.h
> > @@ -128,8 +128,18 @@ rte_net_intel_cksum_flags_prepare(struct rte_mbuf
> *m, uint64_t ol_flags)
> >       if (!(ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK |
> PKT_TX_TCP_SEG)))
> >               return 0;
>
> I think this test should be updated too with PKT_TX_OUTER_IP_CKSUM.
>
Thanks. Yes, I'll update it too.

>
> >
> > -     if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6))
> > +     if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6)) {
> >               inner_l3_offset += m->outer_l2_len + m->outer_l3_len;
> > +             /*
> > +              * prepare outer ipv4 header checksum by setting it to 0,
> > +              * in order to be computed by hardware NICs.
> > +              */
> > +             if (ol_flags & PKT_TX_OUTER_IP_CKSUM) {
> > +                     ipv4_hdr = rte_pktmbuf_mtod_offset(m,
> > +                                     struct rte_ipv4_hdr *,
> m->outer_l2_len);
> > +                     ipv4_hdr->hdr_checksum = 0;
> > +             }
> > +     }
>
> What about outer L4 checksum? Does it requires the same than inner?
>
I am using XL710 for my testing with i40e dpdk driver. AFAIK, It doesn't
support outer l4 checksum. I am not sure if other Intel NICs support it.


> >
> >       /*
> >        * Check if headers are fragmented.
> > --
> > 2.17.1
> >
>