path: root/net/ipv4/tcp_output.c
diff options
authorYuchung Cheng <ycheng@google.com>2019-01-16 15:05:30 -0800
committerDavid S. Miller <davem@davemloft.net>2019-01-17 15:12:26 -0800
commit7ae189759cc48cf8b54beebff566e9fd2d4e7d7c (patch)
tree352db05710fad943494d48107a6fb4d7555d0a70 /net/ipv4/tcp_output.c
parenttcp: always timestamp on every skb transmission (diff)
tcp: always set retrans_stamp on recovery
Previously TCP socket's retrans_stamp is not set if the retransmission has failed to send. As a result if a socket is experiencing local issues to retransmit packets, determining when to abort a socket is complicated w/o knowning the starting time of the recovery since retrans_stamp may remain zero. This complication causes sub-optimal behavior that TCP may use the latest, instead of the first, retransmission time to compute the elapsed time of a stalling connection due to local issues. Then TCP may disrecard TCP retries settings and keep retrying until it finally succeed: not a good idea when the local host is already strained. The simple fix is to always timestamp the start of a recovery. It's worth noting that retrans_stamp is also used to compare echo timestamp values to detect spurious recovery. This patch does not break that because retrans_stamp is still later than when the original packet was sent. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_output.c')
1 files changed, 4 insertions, 5 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 57a56e205070..d2d494c74811 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2963,13 +2963,12 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS;
tp->retrans_out += tcp_skb_pcount(skb);
- /* Save stamp of the first retransmit. */
- if (!tp->retrans_stamp)
- tp->retrans_stamp = tcp_skb_timestamp(skb);
+ /* Save stamp of the first (attempted) retransmit. */
+ if (!tp->retrans_stamp)
+ tp->retrans_stamp = tcp_skb_timestamp(skb);
if (tp->undo_retrans < 0)
tp->undo_retrans = 0;
tp->undo_retrans += tcp_skb_pcount(skb);