netdev - Re: [bpf-next PATCH 3/3] samples/bpf: xdp_fwd explain bpf_fib

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Message-ID: <aae3554f-2d55-d2d1-8cd8-2481ca923469@gmail.com>
Date:   Wed, 7 Aug 2019 11:52:56 -0600
From:   David Ahern <dsahern@...il.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     xdp-newbies@...r.kernel.org, a.s.protopopov@...il.com
Subject: Re: [bpf-next PATCH 3/3] samples/bpf: xdp_fwd explain bpf_fib_lookup
 return codes

On 8/7/19 6:36 AM, Jesper Dangaard Brouer wrote:
> Make it clear that this XDP program depend on the network
> stack to do the ARP resolution.  This is connected with the
> BPF_FIB_LKUP_RET_NO_NEIGH return code from bpf_fib_lookup().
> 
> Another common mistake (seen via XDP-tutorial) is that users
> don't realize that sysctl net.ipv{4,6}.conf.all.forwarding
> setting is honored by bpf_fib_lookup.
> 
> Reported-by: Anton Protopopov <a.s.protopopov@...il.com>
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> ---
>  samples/bpf/xdp_fwd_kern.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 

Reviewed-by: David Ahern <dsahern@...il.com>