From: Martin KaFai Lau <kafai@fb.com>
To: Eric Dumazet <edumazet@google.com>
Cc: netdev <netdev@vger.kernel.org>, Kernel Team <kernel-team@fb.com>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: [RFC PATCH net] tcp: Update pcount after skb_pull() during mtu probing
Date: Fri, 5 Jun 2015 11:02:55 -0700 [thread overview]
Message-ID: <20150605180254.GC2951343@devbig242.prn2.facebook.com> (raw)
In-Reply-To: <CANn89iLd1bqCOxbALcDNzi--Hn8A970HmvM2__ryzjwSbOwZ6Q@mail.gmail.com>
On Fri, Jun 05, 2015 at 09:53:51AM -0700, Eric Dumazet wrote:
> Sounds good, although I would simply get rid of all this complexity in
> this very unlikely path.
>
> Would you instead try the following ?
>
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index eeb59befaf06867b00e1dd6ded7742b2f0bcd821..41ef2c96b2e810e289d6d773e4be09c493b99c09
> 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -1987,16 +1987,7 @@ static int tcp_mtu_probe(struct sock *sk)
> } else {
> TCP_SKB_CB(nskb)->tcp_flags |=
> TCP_SKB_CB(skb)->tcp_flags &
> ~(TCPHDR_FIN|TCPHDR_PSH);
> - if (!skb_shinfo(skb)->nr_frags) {
> - skb_pull(skb, copy);
> - if (skb->ip_summed != CHECKSUM_PARTIAL)
> - skb->csum = csum_partial(skb->data,
> - skb->len, 0);
> - } else {
> - __pskb_trim_head(skb, copy);
> - tcp_set_skb_tso_segs(sk, skb, mss_now);
> - }
> - TCP_SKB_CB(skb)->seq += copy;
> + tcp_trim_head(sk, skb, copy);
tcp_trim_head() does not take the mss_now.
Is it fine to have mss_now <= tcp_skb_mss(skb)? or we can depend on
the tcp_init_tso_segs() in the tcp_write_xmit() to take care of it?
next prev parent reply other threads:[~2015-06-05 18:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-05 16:16 [RFC PATCH net] tcp: Update pcount after skb_pull() during mtu probing Martin KaFai Lau
2015-06-05 16:53 ` Eric Dumazet
2015-06-05 18:02 ` Martin KaFai Lau [this message]
2015-06-05 21:23 ` Eric Dumazet
2015-06-05 23:02 ` Martin KaFai Lau
2015-06-05 23:45 ` Eric Dumazet
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