[PATCH net] tcp: refresh tp timestamp before tcp_mtu_probe()

[Eric Dumazet]

From: Eric Dumazet 

In the unlikely event tcp_mtu_probe() is sending a packet, we
want tp->tcp_mstamp being as accurate as possible. 

This means we need to call tcp_mstamp_refresh() a bit earlier in
tcp_write_xmit().

Fixes: 385e20706fac ("tcp: use tp->tcp_mstamp in output path")
Signed-off-by: Eric Dumazet 
---
 net/ipv4/tcp_output.c |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 
1151870018e345592853b035a0902121c41e268d..ae60dd3faed0adc71731bc686f878afd4c628d32
 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2239,6 +2239,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int 
mss_now, int nonagle,
 
sent_pkts = 0;
 
+   tcp_mstamp_refresh(tp);
if (!push_one) {
/* Do MTU probing. */
result = tcp_mtu_probe(sk);
@@ -2250,7 +2251,6 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int 
mss_now, int nonagle,
}
 
max_segs = tcp_tso_segs(sk, mss_now);
-   tcp_mstamp_refresh(tp);
while ((skb = tcp_send_head(sk))) {
unsigned int limit;
 

Re: [PATCH net] tcp: refresh tp timestamp before tcp_mtu_probe()

[David Miller]

From: Eric Dumazet 
Date: Thu, 26 Oct 2017 21:21:40 -0700

> From: Eric Dumazet 
> 
> In the unlikely event tcp_mtu_probe() is sending a packet, we
> want tp->tcp_mstamp being as accurate as possible. 
> 
> This means we need to call tcp_mstamp_refresh() a bit earlier in
> tcp_write_xmit().
> 
> Fixes: 385e20706fac ("tcp: use tp->tcp_mstamp in output path")
> Signed-off-by: Eric Dumazet 

Applied and queued up for -stable.