netdev - Re: [net-next PATCH v3 2/3] e1000: add initial XDP support

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Message-ID: <1473723968.18970.111.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Mon, 12 Sep 2016 16:46:08 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     John Fastabend <john.fastabend@...il.com>, bblanco@...mgrid.com,
        jeffrey.t.kirsher@...el.com, brouer@...hat.com,
        davem@...emloft.net, xiyou.wangcong@...il.com,
        intel-wired-lan@...ts.osuosl.org, u9012063@...il.com,
        netdev@...r.kernel.org
Subject: Re: [net-next PATCH v3 2/3] e1000: add initial XDP support

On Mon, 2016-09-12 at 16:07 -0700, Alexei Starovoitov wrote:

> yep. there are various ways to shoot yourself in the foot with xdp.
> The simplest program that drops all the packets will make the box unpingable.

Well, my comment was about XDP_TX only, not about XDP_DROP or driving a
scooter on 101 highway ;)

This XDP_TX thing was one of the XDP marketing stuff, but there is
absolutely no documentation on it, warning users about possible
limitations/outcomes.

BTW, I am not sure mlx4 implementation even works, vs BQL :

mlx4_en_xmit_frame() does not call netdev_tx_sent_queue(),
but tx completion will call netdev_tx_completed_queue() -> crash

Do we have one test to validate that a XDP_TX implementation is actually
correct ?