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Merge branch 'fix-DCTCP-delayed-ACK'

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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2018-07-13 18:30:19 -07:00
commit 6bed5e2607
3 changed files with 4 additions and 33 deletions
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2
include/net/tcp.h
View File

@ -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() */

31
net/ipv4/tcp_dctcp.c
View File

@ -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;

4
net/ipv4/tcp_output.c
View File

@ -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.