When TLP fails to send new packet because of receive window
limit or other reasons, it should fall back to retransmit
the last packet, instead of resorting to RTO.
Signed-off-by: Yuchung Cheng <ych...@google.com>
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Nanditad Dukkipati <nandi...@google.com>
---
net/ipv4/tcp_output.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index deb944b..4f238bb 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2226,7 +2226,7 @@ static bool skb_still_in_host_queue(const struct sock *sk,
return false;
}
-/* When probe timeout (PTO) fires, send a new segment if one exists, else
+/* When probe timeout (PTO) fires, try send a new segment if possible, else
* retransmit the last segment.
*/
void tcp_send_loss_probe(struct sock *sk)
@@ -2237,9 +2237,14 @@ void tcp_send_loss_probe(struct sock *sk)
int mss = tcp_current_mss(sk);
int err = -1;
- if (tcp_send_head(sk)) {
+ skb = tcp_send_head(sk);
+ if (skb) {
err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
- goto rearm_timer;
+ if (!err)
+ goto rearm_timer;
+ skb = tcp_write_queue_prev(sk, skb);
+ } else {
+ skb = tcp_write_queue_tail(sk);
}
/* At most one outstanding TLP retransmission. */
@@ -2247,7 +2252,6 @@ void tcp_send_loss_probe(struct sock *sk)
goto rearm_timer;
/* Retransmit last segment. */
- skb = tcp_write_queue_tail(sk);
if (WARN_ON(!skb))
goto rearm_timer;
@@ -2262,7 +2266,7 @@ void tcp_send_loss_probe(struct sock *sk)
if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss,
GFP_ATOMIC)))
goto rearm_timer;
- skb = tcp_write_queue_tail(sk);
+ skb = tcp_write_queue_next(sk, skb);
}
if (WARN_ON(!skb || !tcp_skb_pcount(skb)))
--
2.4.3.573.g4eafbef
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