xref: /openbmc/linux/net/ipv4/tcp_dctcp.h (revision 842ed298)
1 #ifndef _TCP_DCTCP_H
2 #define _TCP_DCTCP_H
3 
4 static inline void dctcp_ece_ack_cwr(struct sock *sk, u32 ce_state)
5 {
6 	struct tcp_sock *tp = tcp_sk(sk);
7 
8 	if (ce_state == 1)
9 		tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
10 	else
11 		tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
12 }
13 
14 /* Minimal DCTP CE state machine:
15  *
16  * S:	0 <- last pkt was non-CE
17  *	1 <- last pkt was CE
18  */
19 static inline void dctcp_ece_ack_update(struct sock *sk, enum tcp_ca_event evt,
20 					u32 *prior_rcv_nxt, u32 *ce_state)
21 {
22 	u32 new_ce_state = (evt == CA_EVENT_ECN_IS_CE) ? 1 : 0;
23 
24 	if (*ce_state != new_ce_state) {
25 		/* CE state has changed, force an immediate ACK to
26 		 * reflect the new CE state. If an ACK was delayed,
27 		 * send that first to reflect the prior CE state.
28 		 */
29 		if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER) {
30 			dctcp_ece_ack_cwr(sk, *ce_state);
31 			__tcp_send_ack(sk, *prior_rcv_nxt);
32 		}
33 		inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
34 	}
35 	*prior_rcv_nxt = tcp_sk(sk)->rcv_nxt;
36 	*ce_state = new_ce_state;
37 	dctcp_ece_ack_cwr(sk, new_ce_state);
38 }
39 
40 #endif
41