On 22 Jun 2019, at 19:17, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <t...@redhat.com>
>
> The bpf_redirect_map() helper used by XDP programs doesn't return any
> indication of whether it can successfully redirect to the map index it was
> given. Instead, BPF programs have to track this themselves, leading to
> programs using duplicate maps to track which entries are populated in the
> devmap.
>
> This patch fixes this by moving the map lookup into the bpf_redirect_map()
> helper, which makes it possible to return failure to the eBPF program. The
> lower bits of the flags argument is used as the return code, which means
> that existing users who pass a '0' flag argument will get XDP_ABORTED.
>
> With this, a BPF program can check the return code from the helper call and
> react by, for instance, substituting a different redirect. This works for
> any type of map used for redirect.
>
> Signed-off-by: Toke Høiland-Jørgensen <t...@redhat.com>
Acked-by: Jonathan Lemon <jonathan.le...@gmail.com>
