From: Sean Tranchetti <stran...@codeaurora.org>
Date: Tue, 28 May 2019 12:22:54 -0600
> Currently, when resegmenting an unexpected UDP GRO packet, the full UDP
> checksum will be calculated for every new SKB created by skb_segment()
> because the netdev features passed in by udp_rcv_segment() lack any
> information about checksum offload capabilities.
>
> Usually, we have no need to perform this calculation again, as
> 1) The GRO implementation guarantees that any packets making it to the
> udp_rcv_segment() function had correct checksums, and, more
> importantly,
> 2) Upon the successful return of udp_rcv_segment(), we immediately pull
> the UDP header off and either queue the segment to the socket or
> hand it off to a new protocol handler.
>
> Unless userspace has set the IP_CHECKSUM sockopt to indicate that they
> want the final checksum values, we can pass the needed netdev feature
> flags to __skb_gso_segment() to avoid checksumming each segment in
> skb_segment().
>
> Fixes: cf329aa42b66 ("udp: cope with UDP GRO packet misdirection")
> Cc: Paolo Abeni <pab...@redhat.com>
> Cc: Subash Abhinov Kasiviswanathan <subas...@codeaurora.org>
> Signed-off-by: Sean Tranchetti <stran...@codeaurora.org>
I've decided to apply this to 'net', thank you.
