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authorYuchung Cheng <ycheng@google.com>2018-08-09 09:38:09 -0700
committerDavid S. Miller <davem@davemloft.net>2018-08-11 11:31:35 -0700
commit466466dc6c28ca9dc401f10e235b9cde9a7c9162 (patch)
treee3c233a4a6ce5a2f77bad3365ea9bbaf739b3f36 /net/ipv4
parent8a8a894ebbc23f52669b80c2ca5bf62d75267324 (diff)
tcp: mandate a one-time immediate ACK
Add a new flag to indicate a one-time immediate ACK. This flag is occasionaly set under specific TCP protocol states in addition to the more common quickack mechanism for interactive application. In several cases in the TCP code we want to force an immediate ACK but do not want to call tcp_enter_quickack_mode() because we do not want to forget the icsk_ack.pingpong or icsk_ack.ato state. 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')
-rw-r--r--net/ipv4/tcp_input.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 715d541b52dd..b8849588c440 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5179,7 +5179,9 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
(tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat ||
__tcp_select_window(sk) >= tp->rcv_wnd)) ||
/* We ACK each frame or... */
- tcp_in_quickack_mode(sk)) {
+ tcp_in_quickack_mode(sk) ||
+ /* Protocol state mandates a one-time immediate ACK */
+ inet_csk(sk)->icsk_ack.pending & ICSK_ACK_NOW) {
send_now:
tcp_send_ack(sk);
return;