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Date:   Wed, 28 Nov 2018 11:44:37 +0100
From:   Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
To:     Kalle Valo <kvalo@codeaurora.org>
Cc:     linux-wireless@vger.kernel.org, nbd@nbd.name
Subject: Re: [RFC 0/5] add XDP support to mt76x2e/mt76x0e drivers
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> Lorenzo Bianconi <lorenzo.bianconi@redhat.com> writes:
> 
> > This series is intended as a playground to start experimenting/developing
> > with XDP/eBPF over WiFi and collect ideas/concerns about it.
> > Introduce XDP support to mt76x2e/mt76x0e drivers. Currently supported
> > actions are:
> > - XDP_PASS
> > - XDP_ABORTED
> > - XDP_DROP
> > Introduce ndo_bpf mac80211 callback in order to to load a bpf
> > program into low level driver XDP rx hook.
> > This series has been tested through a simple bpf program (available here:
> > https://github.com/LorenzoBianconi/bpf-workspace/tree/master/mt76_xdp_stats)
> > used to count frame types received by the device.
> > Possible eBPF use cases could be:
> > - implement new statistics through bpf maps
> > - implement fast packet filtering (e.g in monitor mode)
> > - ...

Hi Kalle,

> 
> This is most likely a stupid question, but why do this in the driver and
> not in mac80211 so that all drivers could benefit from it? I guess there
> are reasons for that, I just can't figure that out.
> 
> -- 
> Kalle Valo

I thought about that possibility (and I think it is definitely valuable) but
I preferred to work as close as possible to the hw running the bpf program
before skb allocation. My primary goal when I started thinking about eBPF over
WiFi was to perform fast packet filtering.
I think these two possibility are not mutually exclusive, we can fall-back to
mac80211 if hw driver does not support XDP.
This is an early stage implementation, at this point I would collect other
people opinions/concerns about using bpf/xdp directly on 802.11 frames.

Regards,
Lorenzo