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Commit 6bed5e26 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'fix-DCTCP-delayed-ACK' 



Yuchung Cheng says:

====================
fix DCTCP delayed ACK

This patch series addresses the issue that sometimes DCTCP
fail to acknowledge the latest sequence and result in sender timeout
if inflight is small.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 5fc853cc a69258f7

include/net/tcp.h

+0 −2
Original line number Diff line number Diff line
@@ -912,8 +912,6 @@ enum tcp_ca_event { 
	CA_EVENT_LOSS,		/* loss timeout */

	CA_EVENT_ECN_NO_CE,	/* ECT set, but not CE marked */

	CA_EVENT_ECN_IS_CE,	/* received CE marked IP packet */

	CA_EVENT_DELAYED_ACK,	/* Delayed ack is sent */

	CA_EVENT_NON_DELAYED_ACK,

};



/* Information about inbound ACK, passed to cong_ops->in_ack_event() */

net/ipv4/tcp_dctcp.c

+4 −27
Original line number Diff line number Diff line
@@ -55,7 +55,6 @@ struct dctcp { 
	u32 dctcp_alpha;

	u32 next_seq;

	u32 ce_state;

	u32 delayed_ack_reserved;

	u32 loss_cwnd;

};
@@ -96,7 +95,6 @@ static void dctcp_init(struct sock *sk) 


		ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);



		ca->delayed_ack_reserved = 0;

		ca->loss_cwnd = 0;

		ca->ce_state = 0;
@@ -134,7 +132,8 @@ static void dctcp_ce_state_0_to_1(struct sock *sk) 
	/* State has changed from CE=0 to CE=1 and delayed

	 * ACK has not sent yet.

	 */

	if (!ca->ce_state && ca->delayed_ack_reserved) {

	if (!ca->ce_state &&

	    inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER) {

		u32 tmp_rcv_nxt;



		/* Save current rcv_nxt. */
@@ -164,7 +163,8 @@ static void dctcp_ce_state_1_to_0(struct sock *sk) 
	/* State has changed from CE=1 to CE=0 and delayed

	 * ACK has not sent yet.

	 */

	if (ca->ce_state && ca->delayed_ack_reserved) {

	if (ca->ce_state &&

	    inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER) {

		u32 tmp_rcv_nxt;



		/* Save current rcv_nxt. */
@@ -248,25 +248,6 @@ static void dctcp_state(struct sock *sk, u8 new_state) 
	}

}



static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)

{

	struct dctcp *ca = inet_csk_ca(sk);



	switch (ev) {

	case CA_EVENT_DELAYED_ACK:

		if (!ca->delayed_ack_reserved)

			ca->delayed_ack_reserved = 1;

		break;

	case CA_EVENT_NON_DELAYED_ACK:

		if (ca->delayed_ack_reserved)

			ca->delayed_ack_reserved = 0;

		break;

	default:

		/* Don't care for the rest. */

		break;

	}

}



static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)

{

	switch (ev) {
@@ -276,10 +257,6 @@ static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev) 
	case CA_EVENT_ECN_NO_CE:

		dctcp_ce_state_1_to_0(sk);

		break;

	case CA_EVENT_DELAYED_ACK:

	case CA_EVENT_NON_DELAYED_ACK:

		dctcp_update_ack_reserved(sk, ev);

		break;

	default:

		/* Don't care for the rest. */

		break;

net/ipv4/tcp_output.c

+0 −4
Original line number Diff line number Diff line
@@ -3523,8 +3523,6 @@ void tcp_send_delayed_ack(struct sock *sk) 
	int ato = icsk->icsk_ack.ato;

	unsigned long timeout;



	tcp_ca_event(sk, CA_EVENT_DELAYED_ACK);



	if (ato > TCP_DELACK_MIN) {

		const struct tcp_sock *tp = tcp_sk(sk);

		int max_ato = HZ / 2;
@@ -3581,8 +3579,6 @@ void tcp_send_ack(struct sock *sk) 
	if (sk->sk_state == TCP_CLOSE)

		return;



	tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK);



	/* We are not putting this on the write queue, so

	 * tcp_transmit_skb() will set the ownership to this

	 * sock.