netdev - Re: [PATCH net-next 1/2] openvswitch: add tunnel protocol to sw_flow

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Date:	Wed, 30 Sep 2015 13:13:56 -0700
From:	Pravin Shelar <pshelar@...ira.com>
To:	Jiri Benc <jbenc@...hat.com>
Cc:	netdev <netdev@...r.kernel.org>,
	"dev@...nvswitch.org" <dev@...nvswitch.org>
Subject: Re: [PATCH net-next 1/2] openvswitch: add tunnel protocol to sw_flow_key

On Wed, Sep 30, 2015 at 12:09 AM, Jiri Benc <jbenc@...hat.com> wrote:
> On Tue, 29 Sep 2015 13:41:34 -0700, Pravin Shelar wrote:
>> We can add rather add TUNNEL_IPV6 flag to distinguish IPv4 and IPv6
>> tunnel keys. This can be stored in ip_tunnel_key.tun_flags.
>
> Not really. This was my original approach, too, but openvswitch is not
> the only user of struct ip_tunnel_key, and in the lwtunnel core,
> tun_flags are handled in the way that makes this impractical. Most
> importantly, the tun_flags value is directly taken from/stored to
> LWTUNNEL_IP_FLAGS/LWTUNNEL_IP6_FLAGS netlink attributes in
> net/ipv4/ip_tunnel_core.c. This would mean complicated masking, etc.
>
How is it impractical ? Userspace can set flag for IPv6 tunnel info.
That should be easy.

IPv6 bit can not be masked anyways so I do not see problem with
masking this flag due to the new bit.

Since this field is exposed to userspace. TUNNEL_* flags needs to be
moved to uapi header.


>> That also saves space in flow key.
>
> The field was added to a 2 byte hole in the struct sw_flow_key (leaving
> still 1 byte free), thus there's no additional space used.
>
>  Jiri
>
> --
> Jiri Benc
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