From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next 6/6] net: Implmement RFC 6936 (zero RX csums
 for UDP/IPv6)
Date: Mon, 07 Apr 2014 13:16:33 -0400 (EDT)
Message-ID: <20140407.131633.1635128478858805272.davem@davemloft.net>
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From: Tom Herbert <therbert@google.com>
Date: Fri, 4 Apr 2014 17:28:24 -0700 (PDT)

> RFC 6936 relaxes the requirement of RFC 2460 that UDP/IPv6 packets which
> are received with a zero UDP checksum value must be dropped. RFC 6936
> allow zero checksums to support tunnels over UDP.
> 
> This patch adds a new socket option UDP_CHECK6_ZERO_OKAY whcih can be
> set on a UDP socket to indicate that a zero checksum is acceptable
> (e.g. the socket is for a tunnel). The ip6 checksum and UDP receive
> functions were updated accordingly to deal with this.
> 
> Signed-off-by: Tom Herbert <therbert@google.com>

I see you reply to this later and say we can use sk_no_check.

Are you really sure?  This might create a surprise for someone
inadvertantly setting that now and expecting it to have a very
specific effect only for ipv4 UDP sockets.

The safest thing to do is to create the new option, then there
is no discrepancy.