| Message ID | 20180709112554.32754-1-joakim.misund@gmail.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | tcp: Added check of destination specific CC before sending syn/ack | expand |
On 07/09/2018 04:25 AM, joakim.misund@gmail.com wrote: > From: Joakim Misund <joakim.misund@gmail.com> > > Issue: > Currently TCP stack does not check for a destination specific CC before responding to a syn with a syn/ack. > The system wide default CC is used. If the default CC does not need ECN, but the destination specific does, > the syn/ack will not carry ECT(0) which makes it eligible to drop instead of being marked at routers. > In an ECN-based network ECN marks are frequent (likely) and packet not carrying ECT(0) are likely to be dropped. > This leads to slow connection establishment, and in worst case the establishment can fail. > > Signed-off-by: Joakim Misund <joakim.misund@gmail.com> > --- > include/net/tcp.h | 1 + > net/ipv4/tcp_input.c | 2 ++ > net/ipv4/tcp_output.c | 2 +- > 3 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/include/net/tcp.h b/include/net/tcp.h > index af3ec72d5d41..347c59ac0a72 100644 > --- a/include/net/tcp.h > +++ b/include/net/tcp.h > @@ -545,6 +545,7 @@ void tcp_send_loss_probe(struct sock *sk); > bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); > void tcp_skb_collapse_tstamp(struct sk_buff *skb, > const struct sk_buff *next_skb); > +void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst); > > /* tcp_input.c */ > void tcp_rearm_rto(struct sock *sk); > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index 8e5522c6833a..973e3b5b0516 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -6401,6 +6401,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, > isn = af_ops->init_seq(skb); > } > > + tcp_ca_dst_init(sk, dst); At this point sk is not locked (and will not be) Multiple cpus can handle SYN packets in // so this would be racy. You need to solve this problem in another way. Thanks.
diff --git a/include/net/tcp.h b/include/net/tcp.h index af3ec72d5d41..347c59ac0a72 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -545,6 +545,7 @@ void tcp_send_loss_probe(struct sock *sk); bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); void tcp_skb_collapse_tstamp(struct sk_buff *skb, const struct sk_buff *next_skb); +void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst); /* tcp_input.c */ void tcp_rearm_rto(struct sock *sk); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 8e5522c6833a..973e3b5b0516 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6401,6 +6401,8 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, isn = af_ops->init_seq(skb); } + tcp_ca_dst_init(sk, dst); + tcp_ecn_create_request(req, skb, sk, dst); if (want_cookie) { diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 8e08b409c71e..550597acd48c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3256,7 +3256,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, } EXPORT_SYMBOL(tcp_make_synack); -static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) +void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) { struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_congestion_ops *ca;