Subject: Re: [PATCH v6 01/12] bpf: add XDP prog type for early driver filter

From: Jesper Dangaard Brouer <[email-masked]>
Date: Mon, 11 Jul 2016 15:53:46 +0200

On Sun, 10 Jul 2016 16:04:16 -0500
Tom Herbert <[email-masked]> wrote:

> > +/* User return codes for XDP prog type.
> > + * A valid XDP program must return one of these defined values. All other
> > + * return codes are reserved for future use. Unknown return codes will result
> > + * in driver-dependent behavior.
> > + */
> > +enum xdp_action {
> > +       XDP_DROP,
> > +       XDP_PASS,  
> 
> I think that we should be able to distinguish an abort in BPF program
> from a normal programmatic drop. e.g.:
> 
> enum xdp_action {
>       XDP_ABORTED = 0,
>       XDP_DROP,
>       XDP_PASS,
> };

I agree.  And maybe we can re-use the bpf_warn_invalid_xdp_action() call
to keep the branch/jump-table as simple as possible, handling the
distinguishing on the slow path.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer