netdev - Re: [PATCH net-next 7/8] net/mlx5e: XDP TX forwarding support

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Message-ID: <84150f05-7eb3-d35c-32fd-4b9853f6f114@gmail.com>
Date:   Wed, 21 Sep 2016 10:57:34 +0300
From:   Tariq Toukan <ttoukan.linux@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Eran Ben Elisha <eranbe@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Rana Shahout <ranas@...lanox.com>
Subject: Re: [PATCH net-next 7/8] net/mlx5e: XDP TX forwarding support


On 20/09/2016 6:40 PM, Alexei Starovoitov wrote:
> On Tue, Sep 20, 2016 at 03:53:10PM +0300, Tariq Toukan wrote:
>>>>> +	case XDP_ABORTED:
>>>> It is not clearly defined, but I believe XDP_ABORTED should also result
>>>> in a warning (calling bpf_warn_invalid_xdp_action(act)).
>> I'll add this.
> Certainly NOT.
> XDP_ABORTED is an exception case when program does divide by zero.
> It should NOT do bpf_warn. It must drop the packet.
> We discussed it several months ago.
> See mlx4/en_rx.c for canonical implementation.
>
This is also the example given here:
https://prototype-kernel.readthedocs.io/en/latest/networking/XDP/implementation/xdp_actions.html#code-example

I prefer to align with the documentation (and with current mlx4 driver 
code), which means keeping the XDP_ABORTED w/o a warning.
Anyway, I don't think this should block the coming V2. If you decide to 
change documentation/specification, we will simply adjust our drivers 
accordingly.

Thanks,
Tariq.