Subject: Re: [PATCH bpf V7 1/7] selftests/bpf: xdp_hw_metadata default disable bpf_printk

From: Simon Horman <[email-masked]>
Date: Mon, 10 Apr 2023 16:50:33 +0200

On Sat, Apr 08, 2023 at 09:24:41PM +0200, Jesper Dangaard Brouer wrote:
> The tool xdp_hw_metadata can be used by driver developers
> implementing XDP-hints kfuncs.  The tool transfers the
> XDP-hints via metadata information to an AF_XDP userspace
> process. When everything works the bpf_printk calls are
> unncesssary.  Thus, disable bpf_printk by default, but
> make it easy to reenable for driver developers to use
> when debugging their driver implementation.
> 
> This also converts bpf_printk "forwarding UDP:9091 to AF_XDP"
> into a code comment.  The bpf_printk's that are important
> to the driver developers is when bpf_xdp_adjust_meta fails.
> The likely mistake from driver developers is expected to
> be that they didn't implement XDP metadata adjust support.
> 
> Signed-off-by: Jesper Dangaard Brouer <[email-masked]>
> ---
>  .../testing/selftests/bpf/progs/xdp_hw_metadata.c  |   16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> index 4c55b4d79d3d..980eb60d8e5b 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> @@ -5,6 +5,19 @@
>  #include <bpf/bpf_helpers.h>
>  #include <bpf/bpf_endian.h>
>  
> +/* Per default below bpf_printk() calls are disabled.  Can be
> + * reenabled manually for convenience by XDP-hints driver developer,
> + * when troublshooting the drivers kfuncs implementation details.

Hi Jesper,

a minor nit from my side:

nit: s/troublshooting/troubleshooting/

...