diff options
| author | Wei Wang <weiwan@google.com> | 2020-12-08 09:55:08 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-12-09 16:08:23 -0800 |
| commit | 8ef44b6fe49d2b8d03ba9aa69063612b474f963b (patch) | |
| tree | 74f6edf6c6e959406b20c0abbc457929040e6431 /net/ipv4 | |
| parent | a770bf515613c6e12ae904c3593e26016de99448 (diff) | |
| download | lwn-8ef44b6fe49d2b8d03ba9aa69063612b474f963b.tar.gz lwn-8ef44b6fe49d2b8d03ba9aa69063612b474f963b.zip | |
tcp: Retain ECT bits for tos reflection
For DCTCP, we have to retain the ECT bits set by the congestion control
algorithm on the socket when reflecting syn TOS in syn-ack, in order to
make ECN work properly.
Fixes: ac8f1710c12b ("tcp: reflect tos value received in SYN to the socket")
Reported-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 8391aa29e7a4..595dcc3afac5 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -984,7 +984,8 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst, __tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr); tos = sock_net(sk)->ipv4.sysctl_tcp_reflect_tos ? - tcp_rsk(req)->syn_tos & ~INET_ECN_MASK : + (tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) | + (inet_sk(sk)->tos & INET_ECN_MASK) : inet_sk(sk)->tos; if (!INET_ECN_is_capable(tos) && @@ -1541,7 +1542,9 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen; newinet->inet_id = prandom_u32(); - /* Set ToS of the new socket based upon the value of incoming SYN. */ + /* Set ToS of the new socket based upon the value of incoming SYN. + * ECT bits are set later in tcp_init_transfer(). + */ if (sock_net(sk)->ipv4.sysctl_tcp_reflect_tos) newinet->tos = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK; |