@@ -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;
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 <edumazet@google.com> --- net/ipv4/tcp_ipv4.c | 85 ++++++++++++++++++++++++--------------------- 1 file changed, 45 insertions(+), 40 deletions(-)