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From:   Song Liu <songliubraving@fb.com>
To:     Yafang Shao <laoar.shao@gmail.com>
CC:     "davem@davemloft.net" <davem@davemloft.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] tcp: use data length instead of skb->len in
 tcp_probe
Thread-Topic: [PATCH net-next] tcp: use data length instead of skb->len in
 tcp_probe
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Date:   Thu, 24 May 2018 17:44:46 +0000
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> On May 24, 2018, at 5:48 AM, Yafang Shao <laoar.shao@gmail.com> wrote:
>=20
> skb->len is meaningless to user.
> data length could be more helpful, with which we can easily filter out
> the packet without payload.
>=20
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> ---
> include/trace/events/tcp.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
> index c1a5284..259b991 100644
> --- a/include/trace/events/tcp.h
> +++ b/include/trace/events/tcp.h
> @@ -261,7 +261,7 @@
> 		__entry->dport =3D ntohs(inet->inet_dport);
> 		__entry->mark =3D skb->mark;
>=20
> -		__entry->length =3D skb->len;
> +		__entry->length =3D skb->len - tcp_hdrlen(skb);

We should also rename __entry->length to __entry->data_len, so that whoever
using this field will notice the change.=20

Thanks,
Song


> 		__entry->snd_nxt =3D tp->snd_nxt;
> 		__entry->snd_una =3D tp->snd_una;
> 		__entry->snd_cwnd =3D tp->snd_cwnd;
> @@ -272,7 +272,7 @@
> 		__entry->sock_cookie =3D sock_gen_cookie(sk);
> 	),
>=20
> -	TP_printk("src=3D%pISpc dest=3D%pISpc mark=3D%#x length=3D%d snd_nxt=3D=
%#x snd_una=3D%#x snd_cwnd=3D%u ssthresh=3D%u snd_wnd=3D%u srtt=3D%u rcv_wn=
d=3D%u sock_cookie=3D%llx",
> +	TP_printk("src=3D%pISpc dest=3D%pISpc mark=3D%#x data_len=3D%d snd_nxt=
=3D%#x snd_una=3D%#x snd_cwnd=3D%u ssthresh=3D%u snd_wnd=3D%u srtt=3D%u rcv=
_wnd=3D%u sock_cookie=3D%llx",
> 		  __entry->saddr, __entry->daddr, __entry->mark,
> 		  __entry->length, __entry->snd_nxt, __entry->snd_una,
> 		  __entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
> --=20
> 1.8.3.1
>=20