path: root/net/ipv4/tcp_input.c
diff options
authorYuchung Cheng <ycheng@google.com>2018-08-09 09:38:11 -0700
committerDavid S. Miller <davem@davemloft.net>2018-08-11 11:31:35 -0700
commit15bdd5686c2c61373680b9015e95abf31778e4fd (patch)
tree22ea53be6abfa0c819b4cdcccee8e4da4e4cc6a6 /net/ipv4/tcp_input.c
parenttcp: avoid resetting ACK timer in DCTCP (diff)
tcp: always ACK immediately on hole repairs
RFC 5681 sec 4.2: To provide feedback to senders recovering from losses, the receiver SHOULD send an immediate ACK when it receives a data segment that fills in all or part of a gap in the sequence space. When a gap is partially filled, __tcp_ack_snd_check already checks the out-of-order queue and correctly send an immediate ACK. However when a gap is fully filled, the previous implementation only resets pingpong mode which does not guarantee an immediate ACK because the quick ACK counter may be zero. This patch addresses this issue by marking the one-time immediate ACK flag instead. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b8849588c440..9a09ff3afef2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4735,11 +4735,11 @@ queue_and_out:
if (!RB_EMPTY_ROOT(&tp->out_of_order_queue)) {
- /* RFC2581. 4.2. SHOULD send immediate ACK, when
+ /* RFC5681. 4.2. SHOULD send immediate ACK, when
* gap in queue is filled.
if (RB_EMPTY_ROOT(&tp->out_of_order_queue))
- inet_csk(sk)->icsk_ack.pingpong = 0;
+ inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
if (tp->rx_opt.num_sacks)