Re: [PATCH net v2 1/2] ipv6: constify rt6_nexthop()

[Nick Desaulniers <ndesaulniers@google.com>]

On Mon, Jun 24, 2019 at 7:01 AM Nicolas Dichtel
<nicolas.dichtel@6wind.com> wrote:
>
> There is no functional change in this patch, it only prepares the next one.
>
> rt6_nexthop() will be used by ip6_dst_lookup_neigh(), which uses const
> variables.
>
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>

Also, I think this fixes an issues reported by 0day:
https://groups.google.com/forum/#!searchin/clang-built-linux/const%7Csort:date/clang-built-linux/umkS84jS9m8/GAVVEgNYBgAJ

Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  drivers/net/vrf.c                | 2 +-
>  include/net/ip6_route.h          | 4 ++--
>  net/bluetooth/6lowpan.c          | 4 ++--
>  net/ipv6/ip6_output.c            | 2 +-
>  net/netfilter/nf_flow_table_ip.c | 2 +-
>  5 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
> index 11b9525dff27..311b0cc6eb98 100644
> --- a/drivers/net/vrf.c
> +++ b/drivers/net/vrf.c
> @@ -350,8 +350,8 @@ static int vrf_finish_output6(struct net *net, struct sock *sk,
>  {
>         struct dst_entry *dst = skb_dst(skb);
>         struct net_device *dev = dst->dev;
> +       const struct in6_addr *nexthop;
>         struct neighbour *neigh;
> -       struct in6_addr *nexthop;
>         int ret;
>
>         nf_reset(skb);
> diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
> index 4790beaa86e0..ee7405e759ba 100644
> --- a/include/net/ip6_route.h
> +++ b/include/net/ip6_route.h
> @@ -262,8 +262,8 @@ static inline bool ip6_sk_ignore_df(const struct sock *sk)
>                inet6_sk(sk)->pmtudisc == IPV6_PMTUDISC_OMIT;
>  }
>
> -static inline struct in6_addr *rt6_nexthop(struct rt6_info *rt,
> -                                          struct in6_addr *daddr)
> +static inline const struct in6_addr *rt6_nexthop(const struct rt6_info *rt,
> +                                                const struct in6_addr *daddr)
>  {
>         if (rt->rt6i_flags & RTF_GATEWAY)
>                 return &rt->rt6i_gateway;
> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
> index 19d27bee285e..1555b0c6f7ec 100644
> --- a/net/bluetooth/6lowpan.c
> +++ b/net/bluetooth/6lowpan.c
> @@ -160,10 +160,10 @@ static inline struct lowpan_peer *peer_lookup_dst(struct lowpan_btle_dev *dev,
>                                                   struct in6_addr *daddr,
>                                                   struct sk_buff *skb)
>  {
> -       struct lowpan_peer *peer;
> -       struct in6_addr *nexthop;
>         struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
>         int count = atomic_read(&dev->peer_count);
> +       const struct in6_addr *nexthop;
> +       struct lowpan_peer *peer;

I see the added const, but I'm not sure why the declarations were
reordered?  Here and below. Doesn't matter for code review (doesn't
necessitate a v2).

>
>         BT_DBG("peers %d addr %pI6c rt %p", count, daddr, rt);
>
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 834475717110..21efcd02f337 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -59,8 +59,8 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *
>  {
>         struct dst_entry *dst = skb_dst(skb);
>         struct net_device *dev = dst->dev;
> +       const struct in6_addr *nexthop;
>         struct neighbour *neigh;
> -       struct in6_addr *nexthop;
>         int ret;
>
>         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
> diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> index 241317473114..cdfc33517e85 100644
> --- a/net/netfilter/nf_flow_table_ip.c
> +++ b/net/netfilter/nf_flow_table_ip.c
> @@ -439,9 +439,9 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
>         struct nf_flowtable *flow_table = priv;
>         struct flow_offload_tuple tuple = {};
>         enum flow_offload_tuple_dir dir;
> +       const struct in6_addr *nexthop;
>         struct flow_offload *flow;
>         struct net_device *outdev;
> -       struct in6_addr *nexthop;
>         struct ipv6hdr *ip6h;
>         struct rt6_info *rt;
>
> --
> 2.21.0
>


-- 
Thanks,
~Nick Desaulniers