DCTCP depends on the CA_EVENT_NON_DELAYED_ACK and CA_EVENT_DELAYED_ACK
notifications to keep track if it needs to send an ACK for packets that
were received with a particular ECN state but whose ACK was delayed.
Under some circumstances, for example when a delayed ACK is sent with a
data packet, DCTCP state was not being updated due to a lack of
notification that the previously delayed ACK was sent. As a result, it
would sometimes send a duplicate ACK when a new data packet arrived.
This patch insures that DCTCP's state is correctly updated so it will
not send the duplicate ACK.
Signed-off-by: Lawrence Brakmo <bra...@fb.com>
---
net/ipv4/tcp_output.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f8f6129160dd..41f6ad7a21e4 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -172,6 +172,8 @@ static inline void tcp_event_ack_sent(struct sock *sk,
unsigned int pkts)
__sock_put(sk);
}
tcp_dec_quickack_mode(sk, pkts);
+ if (inet_csk_ack_scheduled(sk))
+ tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK);
inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
}
--
2.17.1
