From 97f5cb640cc002f236c5458eaf5de238d728c28d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 26 May 2020 19:48:49 -0700 Subject: [PATCH] tcp: add tcp_ld_RTO_revert() helper RFC 6069 logic has been implemented for IPv4 only so far, right in the middle of tcp_v4_err() and was error prone. Move this code to one helper, to make tcp_v4_err() more readable and to eventually expand RFC 6069 to IPv6 in the future. Also perform sock_owned_by_user() check a bit sooner. Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Tested-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 85 ++++++++++++++++++++++++--------------------- 1 file changed, 45 insertions(+), 40 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 6789671f0f5a0..f32dcadc91b73 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -403,6 +403,45 @@ void tcp_req_err(struct sock *sk, u32 seq, bool abort) } EXPORT_SYMBOL(tcp_req_err); +/* TCP-LD (RFC 6069) logic */ +static void tcp_ld_RTO_revert(struct sock *sk, u32 seq) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + struct tcp_sock *tp = tcp_sk(sk); + struct sk_buff *skb; + s32 remaining; + u32 delta_us; + + if (sock_owned_by_user(sk)) + return; + + if (seq != tp->snd_una || !icsk->icsk_retransmits || + !icsk->icsk_backoff) + return; + + skb = tcp_rtx_queue_head(sk); + if (WARN_ON_ONCE(!skb)) + return; + + icsk->icsk_backoff--; + icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) : TCP_TIMEOUT_INIT; + icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX); + + tcp_mstamp_refresh(tp); + delta_us = (u32)(tp->tcp_mstamp - tcp_skb_timestamp_us(skb)); + remaining = icsk->icsk_rto - usecs_to_jiffies(delta_us); + + if (remaining > 0) { + inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, + remaining, TCP_RTO_MAX); + } else { + /* RTO revert clocked out retransmission. + * Will retransmit now. + */ + tcp_retransmit_timer(sk); + } +} + /* * This routine is called by the ICMP module when it gets some * sort of error condition. If err < 0 then the socket should @@ -423,17 +462,13 @@ int tcp_v4_err(struct sk_buff *icmp_skb, u32 info) { const struct iphdr *iph = (const struct iphdr *)icmp_skb->data; struct tcphdr *th = (struct tcphdr *)(icmp_skb->data + (iph->ihl << 2)); - struct inet_connection_sock *icsk; struct tcp_sock *tp; struct inet_sock *inet; const int type = icmp_hdr(icmp_skb)->type; const int code = icmp_hdr(icmp_skb)->code; struct sock *sk; - struct sk_buff *skb; struct request_sock *fastopen; u32 seq, snd_una; - s32 remaining; - u32 delta_us; int err; struct net *net = dev_net(icmp_skb->dev); @@ -476,7 +511,6 @@ int tcp_v4_err(struct sk_buff *icmp_skb, u32 info) goto out; } - icsk = inet_csk(sk); tp = tcp_sk(sk); /* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */ fastopen = rcu_dereference(tp->fastopen_rsk); @@ -521,41 +555,12 @@ int tcp_v4_err(struct sk_buff *icmp_skb, u32 info) } err = icmp_err_convert[code].errno; - /* check if icmp_skb allows revert of backoff - * (see draft-zimmermann-tcp-lcd) */ - if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH) - break; - if (seq != tp->snd_una || !icsk->icsk_retransmits || - !icsk->icsk_backoff || fastopen) - break; - - if (sock_owned_by_user(sk)) - break; - - skb = tcp_rtx_queue_head(sk); - if (WARN_ON_ONCE(!skb)) - break; - - icsk->icsk_backoff--; - icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) : - TCP_TIMEOUT_INIT; - icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX); - - - tcp_mstamp_refresh(tp); - delta_us = (u32)(tp->tcp_mstamp - tcp_skb_timestamp_us(skb)); - remaining = icsk->icsk_rto - - usecs_to_jiffies(delta_us); - - if (remaining > 0) { - inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, - remaining, TCP_RTO_MAX); - } else { - /* RTO revert clocked out retransmission. - * Will retransmit now */ - tcp_retransmit_timer(sk); - } - + /* check if this ICMP message allows revert of backoff. + * (see RFC 6069) + */ + if (!fastopen && + (code == ICMP_NET_UNREACH || code == ICMP_HOST_UNREACH)) + tcp_ld_RTO_revert(sk, seq); break; case ICMP_TIME_EXCEEDED: err = EHOSTUNREACH; -- 2.39.5