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

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Date:	Thu, 12 Jun 2014 13:46:50 -0400
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Nandita Dukkipati <nanditad@...gle.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Per Hurtig <per.hurtig@....se>, panweiping3@...il.com,
	Netdev <netdev@...r.kernel.org>,
	Anna Brunström <anna.brunstrom@....se>,
	mohammad.rajiullah@....se, sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v2 1/1] tcp: fixing TLP's FIN recovery

On Thu, Jun 12, 2014 at 1:36 PM, Nandita Dukkipati <nanditad@...gle.com> wrote:
> On Thu, Jun 12, 2014 at 8:28 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> 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>
>
> Acked-by: Nandita Dukkipati <nanditad@...gle.com>

Thanks, Per!

Acked-by: Neal Cardwell <ncardwell@...gle.com>

neal
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