netdev - Re: [bpf-next V4 PATCH 5/8] xdp: introduce xdp_return_frame_rx

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Message-ID: <20180518224606.1dd2edc7@redhat.com>
Date:   Fri, 18 May 2018 22:46:06 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org, Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        BjörnTöpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        makita.toshiaki@....ntt.co.jp
Subject: Re: [bpf-next V4 PATCH 5/8] xdp: introduce xdp_return_frame_rx_napi

On Fri, 18 May 2018 15:34:57 +0200
Jesper Dangaard Brouer <brouer@...hat.com> wrote:

> When sending an xdp_frame through xdp_do_redirect call, then error
> cases can happen where the xdp_frame needs to be dropped, and
> returning an -errno code isn't sufficient/possible any-longer
> (e.g. for cpumap case). This is already fully supported, by simply
> calling xdp_return_frame.
> 
> This patch is an optimization, which provides xdp_return_frame_rx_napi,
> which is a faster variant for these error cases.  It take advantage of
> the protection provided by XDP RX running under NAPI protection.
> 
> This change is mostly relevant for drivers using the page_pool
> allocator as it can take advantage of this. (Tested with mlx5).

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Ups, forgot my SoB... hope it's sufficient to add it this way.

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