netdev - Re: [PATCH v2 1/1] tcp: fixing TLP's FIN recovery

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Date:	Thu, 12 Jun 2014 08:28:36 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Per Hurtig <per.hurtig@....se>
Cc:	panweiping3@...il.com, nanditad@...gle.com, netdev@...r.kernel.org,
	anna.brunstrom@....se, mohammad.rajiullah@....se,
	ncardwell@...gle.com, sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v2 1/1] tcp: fixing TLP's FIN recovery

On Thu, 2014-06-12 at 17:08 +0200, Per Hurtig wrote:
> Fix to a problem observed when losing a FIN segment that does not
> contain data.  In such situations, TLP is unable to recover from
> *any* tail loss and instead adds at least PTO ms to the
> retransmission process, i.e., RTO = RTO + PTO.
> 
> Signed-off-by: Per Hurtig <per.hurtig@....se>
> ---
>  net/ipv4/tcp_output.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index ad7549f..819bf0c 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -2131,9 +2131,7 @@ void tcp_send_loss_probe(struct sock *sk)
>  	if (WARN_ON(!skb || !tcp_skb_pcount(skb)))
>  		goto rearm_timer;
>  
> -	/* Probe with zero data doesn't trigger fast recovery. */
> -	if (skb->len > 0)
> -		err = __tcp_retransmit_skb(sk, skb);
> +	err = __tcp_retransmit_skb(sk, skb);
>  
>  	/* Record snd_nxt for loss detection. */
>  	if (likely(!err))

Thanks a lot Per

Signed-off-by: Eric Dumazet <edumazet@...gle.com>


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