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From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	netdev@vger.kernel.org,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	John Fastabend <john.fastabend@gmail.com>,
	brouer@redhat.com
Subject: Re: [PATCH v7 bpf-next 05/10] veth: Handle xdp_frames in xdp napi ring
Date: Thu, 2 Aug 2018 13:45:48 +0200	[thread overview]
Message-ID: <20180802134548.2230455b@redhat.com> (raw)
In-Reply-To: <1533207314-2572-6-git-send-email-makita.toshiaki@lab.ntt.co.jp>

On Thu,  2 Aug 2018 19:55:09 +0900
Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> wrote:

> +	headroom = frame->data - delta - (void *)frame;

Your calculation of headroom is still adding an assumption that
xdp_frame is located in the top of data area, that is unnecessary.

The headroom can be calculated as:

 headroom = sizeof(struct xdp_frame) + frame->headroom - delta;

> +	skb = veth_build_skb(frame, headroom, len, 0);
> +	if (!skb) {
> +		xdp_return_frame(frame);
> +		goto err;
> +	}
> +
> +	xdp_scrub_frame(frame);

Thanks you for adding a xdp_scrub_frame() instead.

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

  reply	other threads:[~2018-08-02 13:36 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-02 10:55 [PATCH v7 bpf-next 00/10] veth: Driver XDP Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 01/10] net: Export skb_headers_offset_update Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 02/10] veth: Add driver XDP Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 03/10] veth: Avoid drops by oversized packets when XDP is enabled Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 04/10] xdp: Helper function to clear kernel pointers in xdp_frame Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 05/10] veth: Handle xdp_frames in xdp napi ring Toshiaki Makita
2018-08-02 11:45   ` Jesper Dangaard Brouer [this message]
2018-08-02 13:17     ` Toshiaki Makita
2018-08-02 13:53       ` Jesper Dangaard Brouer
2018-08-02 14:10         ` Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 06/10] veth: Add ndo_xdp_xmit Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 07/10] bpf: Make redirect_info accessible from modules Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 08/10] xdp: Helpers for disabling napi_direct of xdp_return_frame Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 09/10] veth: Add XDP TX and REDIRECT Toshiaki Makita
2018-08-02 10:55 ` [PATCH v7 bpf-next 10/10] veth: Support per queue XDP ring Toshiaki Makita

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