@@ -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,
@@ -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;