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-rw-r--r--include/net/inet_connection_sock.h3
-rw-r--r--net/ipv4/tcp_input.c4
2 files changed, 5 insertions, 2 deletions
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 0a6c9e0f2b5a..fa43b82607d9 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -167,7 +167,8 @@ enum inet_csk_ack_state_t {
ICSK_ACK_SCHED = 1,
ICSK_ACK_TIMER = 2,
ICSK_ACK_PUSHED = 4,
- ICSK_ACK_PUSHED2 = 8
+ ICSK_ACK_PUSHED2 = 8,
+ ICSK_ACK_NOW = 16 /* Send the next ACK immediately (once) */
};
void inet_csk_init_xmit_timers(struct sock *sk,
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;