netdev - Re: [PATCH net-next 7/7] vxlan: allow setting ipv6 traffic class

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Message-ID: <20160316115952.463e851c@griffin>
Date:	Wed, 16 Mar 2016 11:59:52 +0100
From:	Jiri Benc <jbenc@...hat.com>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	davem@...emloft.net, alexei.starovoitov@...il.com, tgraf@...g.ch,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next 7/7] vxlan: allow setting ipv6 traffic class

On Fri,  4 Mar 2016 15:15:08 +0100, Daniel Borkmann wrote:
> We can already do that for IPv4, but IPv6 support was missing. Add
> it for vxlan, so it can be used with collect metadata frontends.
> 
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> ---
>  drivers/net/vxlan.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 366a858..d33a434 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -1788,7 +1788,7 @@ static struct rtable *vxlan_get_route(struct vxlan_dev *vxlan,
>  
>  #if IS_ENABLED(CONFIG_IPV6)
>  static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan,
> -					  struct sk_buff *skb, int oif,
> +					  struct sk_buff *skb, int oif, u8 tos,
>  					  const struct in6_addr *daddr,
>  					  struct in6_addr *saddr,
>  					  struct dst_cache *dst_cache,
> @@ -1799,6 +1799,8 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan,
>  	struct flowi6 fl6;
>  	int err;
>  
> +	if (tos && !info)
> +		use_cache = false;
>  	if (use_cache) {
>  		ndst = dst_cache_get_ip6(dst_cache, saddr);
>  		if (ndst)
> @@ -1807,6 +1809,7 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan,
>  
>  	memset(&fl6, 0, sizeof(fl6));
>  	fl6.flowi6_oif = oif;
> +	fl6.flowi6_tos = RT_TOS(tos);

Nothing against this but the reason it was missing was that it's never
used. Unless I'm missing something the IPv6 code does not use this
field at all for lookups.

This patch is not wrong but it's effectively dead code right now.
I'll be happy to be proven wrong, though.

(Sorry for answering after such long time, I'm catching up after a
vacation.)

 Jiri