diff options
| author | Yuchung Cheng <ycheng@google.com> | 2018-10-09 01:32:20 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-10-11 08:26:00 +0300 |
| commit | ffd177dea5c1ee5b717961d041df0778d58f50c0 (patch) | |
| tree | be10e3a3a741632cf00de77b29ae51c4f1787aea /net/ipv4/tcp_dctcp.h | |
| parent | ed792e28c4bd09e9a319d2ad914aa62982cb4c4a (diff) | |
| download | linux-ffd177dea5c1ee5b717961d041df0778d58f50c0.tar.xz | |
tcp: refactor DCTCP ECN ACK handling
DCTCP has two parts - a new ECN signalling mechanism and the response
function to it. The first part can be used by other congestion
control for DCTCP-ECN deployed networks. This patch moves that part
into a separate tcp_dctcp.h to be used by other congestion control
module (like how Yeah uses Vegas algorithmas). For example, BBR is
experimenting such ECN signal currently
https://tinyurl.com/ietf-102-iccrg-bbr2
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Yousuk Seung <ysseung@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_dctcp.h')
| -rw-r--r-- | net/ipv4/tcp_dctcp.h | 40 |
1 files changed, 40 insertions, 0 deletions
diff --git a/net/ipv4/tcp_dctcp.h b/net/ipv4/tcp_dctcp.h new file mode 100644 index 000000000000..d69a77cbd0c7 --- /dev/null +++ b/net/ipv4/tcp_dctcp.h @@ -0,0 +1,40 @@ +#ifndef _TCP_DCTCP_H +#define _TCP_DCTCP_H + +static inline void dctcp_ece_ack_cwr(struct sock *sk, u32 ce_state) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (ce_state == 1) + tp->ecn_flags |= TCP_ECN_DEMAND_CWR; + else + tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR; +} + +/* Minimal DCTP CE state machine: + * + * S: 0 <- last pkt was non-CE + * 1 <- last pkt was CE + */ +static inline void dctcp_ece_ack_update(struct sock *sk, enum tcp_ca_event evt, + u32 *prior_rcv_nxt, u32 *ce_state) +{ + u32 new_ce_state = (evt == CA_EVENT_ECN_IS_CE) ? 1 : 0; + + if (*ce_state != new_ce_state) { + /* CE state has changed, force an immediate ACK to + * reflect the new CE state. If an ACK was delayed, + * send that first to reflect the prior CE state. + */ + if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER) { + dctcp_ece_ack_cwr(sk, *ce_state); + __tcp_send_ack(sk, *prior_rcv_nxt); + } + inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW; + } + *prior_rcv_nxt = tcp_sk(sk)->rcv_nxt; + *ce_state = new_ce_state; + dctcp_ece_ack_cwr(sk, new_ce_state); +} + +#endif |