[PATCH net-next] tcp: timestamp SYN+DATA messages

[PATCH net-next] tcp: timestamp SYN+DATA messages

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

All skb in socket write queue should be properly timestamped.

In case of FastOpen, we special case the SYN+DATA 'message' as we
queue in socket wrote queue the two fallback skbs: 

1) SYN message by itself.
2) DATA segment by itself.

We should make sure these skbs have proper timestamps.

Add a WARN_ON_ONCE() to eventually catch future violations.

Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
---
 net/ipv4/tcp_input.c  |    1 +
 net/ipv4/tcp_output.c |    6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b99003f556d8..e1661f46fd19 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3067,6 +3067,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 			flag |= FLAG_RETRANS_DATA_ACKED;
 		} else {
 			last_ackt = skb->skb_mstamp;
+			WARN_ON_ONCE(last_ackt.v64 == 0);
 			if (!first_ackt.v64)
 				first_ackt = last_ackt;
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index bc0fb0fc7552..a64c51d6f9b6 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2972,6 +2972,12 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 	tcp_connect_queue_skb(sk, data);
 	fo->copied = data->len;
 
+	/* syn_data is about to be sent, we need to take current time stamps
+	 * for the packets that are in write queue : SYN packet and DATA
+	 */
+	skb_mstamp_get(&syn->skb_mstamp);
+	data->skb_mstamp = syn->skb_mstamp;
+
 	if (tcp_transmit_skb(sk, syn_data, 0, sk->sk_allocation) == 0) {
 		tp->syn_data = (fo->copied > 0);
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT);

Re: [PATCH net-next] tcp: timestamp SYN+DATA messages

[Neal Cardwell]

On Sun, Mar 9, 2014 at 8:36 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> All skb in socket write queue should be properly timestamped.
>
> In case of FastOpen, we special case the SYN+DATA 'message' as we
> queue in socket wrote queue the two fallback skbs:
>
> 1) SYN message by itself.
> 2) DATA segment by itself.
>
> We should make sure these skbs have proper timestamps.
>
> Add a WARN_ON_ONCE() to eventually catch future violations.
>
> Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Neal Cardwell <ncardwell@google.com>
> Cc: Yuchung Cheng <ycheng@google.com>

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

neal

Re: [PATCH net-next] tcp: timestamp SYN+DATA messages

[Yuchung Cheng]

On Mon, Mar 10, 2014 at 9:22 AM, Neal Cardwell <ncardwell@google.com> wrote:
> On Sun, Mar 9, 2014 at 8:36 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> From: Eric Dumazet <edumazet@google.com>
>>
>> All skb in socket write queue should be properly timestamped.
>>
>> In case of FastOpen, we special case the SYN+DATA 'message' as we
>> queue in socket wrote queue the two fallback skbs:
>>
>> 1) SYN message by itself.
>> 2) DATA segment by itself.
>>
>> We should make sure these skbs have proper timestamps.
>>
>> Add a WARN_ON_ONCE() to eventually catch future violations.
>>
>> Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
>> Signed-off-by: Eric Dumazet <edumazet@google.com>
>> Cc: Neal Cardwell <ncardwell@google.com>
>> Cc: Yuchung Cheng <ycheng@google.com>
>
> Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>

>
> neal

Re: [PATCH net-next] tcp: timestamp SYN+DATA messages

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sun, 09 Mar 2014 17:36:02 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> All skb in socket write queue should be properly timestamped.
> 
> In case of FastOpen, we special case the SYN+DATA 'message' as we
> queue in socket wrote queue the two fallback skbs: 
> 
> 1) SYN message by itself.
> 2) DATA segment by itself.
> 
> We should make sure these skbs have proper timestamps.
> 
> Add a WARN_ON_ONCE() to eventually catch future violations.
> 
> Fixes: 740b0f1841f6 ("tcp: switch rtt estimations to usec resolution")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks Eric.