On Sat, Jan 13, 2024 at 4:21 PM Ilya Maximets <[email protected]> wrote:
>
> On 12/19/23 15:47, Mike Pattrick wrote:
> > When OVS needs to fallback on the software TSO implementation to segment
> > a packet, it currently doesn't guarantee that IP and TCP checksum
> > offload flags are set. However, it is possible that these is required.
> > This is true in the case of dp_netdev_upcall(), which clears these
> > flags.
> >
> > This patch explicitly sets the appropriate flags when the segmentation
> > flag is removed, to guarantee that packets always end up with correct
> > checksums.
> >
> > Signed-off-by: Mike Pattrick <[email protected]>
> >
> > ---
> >
> > v3: Moved logic from ofproto-dpif-upcall to dp-packet
> > Signed-off-by: Mike Pattrick <[email protected]>
> > ---
> > lib/dp-packet.h | 16 ++++++++++++++--
> > 1 file changed, 14 insertions(+), 2 deletions(-)
> >
> > diff --git a/lib/dp-packet.h b/lib/dp-packet.h
> > index 11aa00723..f91b5e3fb 100644
> > --- a/lib/dp-packet.h
> > +++ b/lib/dp-packet.h
> > @@ -1131,11 +1131,23 @@ dp_packet_hwol_set_tcp_seg(struct dp_packet *b)
> > *dp_packet_ol_flags_ptr(b) |= DP_PACKET_OL_TX_TCP_SEG;
> > }
> >
> > -/* Resets TCP Segmentation flag in packet 'p'. */
> > +/* Resets TCP Segmentation in packet 'p' and adjust flags to indicate
> > + * L3 and L4 checksumming is now required. */
> > static inline void
> > dp_packet_hwol_reset_tcp_seg(struct dp_packet *p)
> > {
> > - *dp_packet_ol_flags_ptr(p) &= ~DP_PACKET_OL_TX_TCP_SEG;
> > + uint64_t ol_flags = *dp_packet_ol_flags_ptr(p)
> > + | DP_PACKET_OL_TX_TCP_CKSUM;
> > +
> > + ol_flags = ol_flags & ~(DP_PACKET_OL_TX_TCP_SEG
> > + | DP_PACKET_OL_RX_L4_CKSUM_MASK
> > + | DP_PACKET_OL_RX_IP_CKSUM_GOOD);
>
> This is a little unclear why we clear all L4 checksum flags,
> but we do not clear IP_CKSUM_BAD. Is there a reason for that?
> If so, we should have a comment here explaining the situation
> as it is not obvious.
Removing BAD is unneeded here. I'll fix that in the next version.
Thanks,
Mike
>
> > +
> > + if (ol_flags & DP_PACKET_OL_TX_IPV4) {
> > + ol_flags |= DP_PACKET_OL_TX_IP_CKSUM;
>
> Nit: Over-indented. One space too far.
>
> > + }
> > +
> > + *dp_packet_ol_flags_ptr(p) = ol_flags;
> > }
> >
> > /* Returns 'true' if the IP header has good integrity and the
>
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