netdev - Re: [PATCH net-next 6/7] samples/bpf: xdp_redirect load XDP dummy prog on TX device

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Date:   Thu, 31 Aug 2017 12:15:36 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Tariq Toukan <tariqt@...lanox.com>
Cc:     netdev@...r.kernel.org, John Fastabend <john.fastabend@...il.com>,
        Eran Ben Elisha <eranbe@...lanox.com>, brouer@...hat.com
Subject: Re: [PATCH net-next 6/7] samples/bpf: xdp_redirect load XDP dummy
 prog on TX device

On Thu, 31 Aug 2017 13:08:22 +0300
Tariq Toukan <tariqt@...lanox.com> wrote:

> Hi Jesper,
> 
> On 29/08/2017 5:38 PM, Jesper Dangaard Brouer wrote:
> >   
> > +/* Redirect require an XDP bpf_prog loaded on the TX device */
> > +SEC("xdp_redirect_dummy")
> > +int xdp_redirect_dummy(struct xdp_md *ctx)
> > +{
> > +	return XDP_PASS;
> > +}
> > +  
> 
> I get a compilation error related to this:
> 
> $ make samples/bpf/
> 
> ...
> LLVM ERROR: 'xdp_redirect_dummy' label emitted multiple times to 
> assembly file
> make[1]: *** [samples/bpf/xdp_redirect_kern.o] Error 1
> make: *** [samples/bpf/] Error 2
> 
> 
> It can be fixed by the following patch.
> I can submit it in a separate mail if you want to.

Ups! - yes please submit an official fix-patch for this!

Below fix looks good to me...

> diff --git a/samples/bpf/xdp_redirect_kern.c 
> b/samples/bpf/xdp_redirect_kern.c
> index 1c90288d0203..8abb151e385f 100644
> --- a/samples/bpf/xdp_redirect_kern.c
> +++ b/samples/bpf/xdp_redirect_kern.c
> @@ -82,7 +82,7 @@ int xdp_redirect_prog(struct xdp_md *ctx)
> 
>   /* Redirect require an XDP bpf_prog loaded on the TX device */
>   SEC("xdp_redirect_dummy")
> -int xdp_redirect_dummy(struct xdp_md *ctx)
> +int xdp_redirect_dummy_prog(struct xdp_md *ctx)
>   {
>          return XDP_PASS;
>   }
> diff --git a/samples/bpf/xdp_redirect_map_kern.c 
> b/samples/bpf/xdp_redirect_map_kern.c
> index 79795d41ad0d..740a529ba84f 100644
> --- a/samples/bpf/xdp_redirect_map_kern.c
> +++ b/samples/bpf/xdp_redirect_map_kern.c
> @@ -84,7 +84,7 @@ int xdp_redirect_map_prog(struct xdp_md *ctx)
> 
>   /* Redirect require an XDP bpf_prog loaded on the TX device */
>   SEC("xdp_redirect_dummy")
> -int xdp_redirect_dummy(struct xdp_md *ctx)
> +int xdp_redirect_dummy_prog(struct xdp_md *ctx)
>   {
>          return XDP_PASS;
>   }

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