Subject: Re: [PATCH net-next v7 1/2] net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS,IP,NSH etc.

From: Martin Varghese <[email-masked]>
Date: Mon, 17 Feb 2020 08:13:51 +0530

On Sun, Feb 16, 2020 at 10:58:30AM -0600, Willem de Bruijn wrote:
> On Fri, Feb 14, 2020 at 11:20 PM Martin Varghese
> <[email-masked]> wrote:
> >
> > From: Martin Varghese <[email-masked]>
> >
> > The Bareudp tunnel module provides a generic L3 encapsulation
> > tunnelling module for tunnelling different protocols like MPLS,
> > IP,NSH etc inside a UDP tunnel.
> >
> > Signed-off-by: Martin Varghese <[email-masked]>
> 
> A few small points
> 
> >  net/ipv4/route.c                     |  48 +++
> >  net/ipv6/ip6_output.c                |  70 ++++
> 
> Both protocols have route.c and ip(6)_output.c files. For the sake of
> consistency, both should ideally be in route.c. Did you choose
> ip6_output.c for a reason?
> 
> There are also a couple of reverse christmas tree violations.
>
In Bareudp.c correct?
Wondering if there is any flag in checkpatch to catch them? 
> > +struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
> > +                                     struct net_device *dev,
> > +                                     struct net *net, __be32 *saddr,
> > +                                     const struct ip_tunnel_info *info,
> > +                                     u8 protocol, bool use_cache)
> > +{
> > +#ifdef CONFIG_DST_CACHE
> > +       struct dst_cache *dst_cache;
> > +#endif
> > +       struct rtable *rt = NULL;
> > +       struct flowi4 fl4;
> > +       __u8 tos;
> > +
> > +       memset(&fl4, 0, sizeof(fl4));
> > +       fl4.flowi4_mark = skb->mark;
> > +       fl4.flowi4_proto = protocol;
> > +       fl4.daddr = info->key.u.ipv4.dst;
> > +       fl4.saddr = info->key.u.ipv4.src;
> > +
> > +       tos = info->key.tos;
> > +       fl4.flowi4_tos = RT_TOS(tos);
> > +#ifdef CONFIG_DST_CACHE
> > +       dst_cache = (struct dst_cache *)&info->dst_cache;
> > +       if (use_cache) {
> > +               rt = dst_cache_get_ip4(dst_cache, saddr);
> > +               if (rt)
> > +                       return rt;
> > +       }
> > +#endif
> 
> This is the same in geneve, but no need to initialize fl4 on a cache
> hit. Then can also be restructured to only have a single #ifdef block.
Yes , We need not initialize fl4 when cache is used.
But i didnt get your point on restructuing to have a single #ifdef block
Could you please give more details