Re: [PATCH net v4] igb: Fix XDP with PTP enabled

From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	Sven Auhagen <sven.auhagen@voleatech.de>,
	intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
	bpf@vger.kernel.org,
	Ilias Apalodimas <ilias.apalodimas@linaro.org>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Richard Cochran <richardcochran@gmail.com>,
	Alexander Duyck <alexander.duyck@gmail.com>,
	Tyler S <tylerjstachecki@gmail.com>,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	brouer@redhat.com
Subject: Re: [PATCH net v4] igb: Fix XDP with PTP enabled
Date: Wed, 19 May 2021 15:34:18 +0200	[thread overview]
Message-ID: <20210519153418.00c4cc42@carbon> (raw)
In-Reply-To: <20210504102827.342f6302@carbon>

Hi Maintainers,

What is the status on this patch?

I don't see this fix being applied on git-trees net or net-next.

[0] 20210503072800.79936-1-kurt@linutronix.de
[1] https://patchwork.kernel.org/project/netdevbpf/patch/20210503072800.79936-1-kurt@linutronix.de/
[2] https://lore.kernel.org/netdev/20210503072800.79936-1-kurt@linutronix.de/

On Tue, 4 May 2021 10:28:27 +0200
Jesper Dangaard Brouer <brouer@redhat.com> wrote:

> On Mon,  3 May 2021 09:28:00 +0200
> Kurt Kanzenbach <kurt@linutronix.de> wrote:
> 
> > When using native XDP with the igb driver, the XDP frame data doesn't point to
> > the beginning of the packet. It's off by 16 bytes. Everything works as expected
> > with XDP skb mode.
> > 
> > Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
> > the timestamp before executing any XDP operations and adjust all other code
> > accordingly. The igc driver does it like that as well.
> > 
> > Tested with Intel i210 card and AF_XDP sockets.
> > 
> > Fixes: 9cbc948b5a20 ("igb: add XDP support")
> > Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>  
> 
> Thanks for fixing this!
> 
> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
> 
> I expect that we/I will (soon) play with getting this area that is
> stored in front of the packet (the XDP data_meta area) described via
> BTF.  This way both xdp_frame and AF_XDP can get structured access (e.g.
> to the PTP timestamp in this case).
> 
> I'll be adding my notes on this project here:
>  https://github.com/xdp-project/xdp-project/blob/master/areas/tsn/
> 
> Looking forward to collaborate on this with you :-)

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