tcp: report ECN_SEEN in tcp_info

Allows ss command (iproute2) to display "ecnseen" if at least one packet
with ECT(0) or ECT(1) or ECN was received by this socket.

"ecn" means ECN was negotiated at session establishment (TCP level)

"ecnseen" means we received at least one packet with ECT fields set (IP
level)

ss -i
...
ESTAB      0      0   192.168.20.110:22  192.168.20.144:38016
ino:5950 sk:f178e400
	 mem:(r0,w0,f0,t0) ts sack ecn ecnseen bic wscale:7,8 rto:210
rtt:12.5/7.5 cwnd:10 send 9.3Mbps rcv_space:14480

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 6b63b310af362ae4a67c858619b76321c6f546f1..7f59ee94698336fb32be6985e9f791d8b5149dfc 100644 (file)
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -111,7 +111,8 @@ enum {
 #define TCPI_OPT_TIMESTAMPS    1
 #define TCPI_OPT_SACK          2
 #define TCPI_OPT_WSCALE                4
-#define TCPI_OPT_ECN           8
+#define TCPI_OPT_ECN           8 /* ECN was negociated at TCP session init */
+#define TCPI_OPT_ECN_SEEN      16 /* we received at least one packet with ECT */
 
 enum tcp_ca_state {
        TCP_CA_Open = 0,

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 131c45f93373464755fb9455adf7c4725b2dab01..4c0da24fb6490791bd15f995655760211b52992a 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2455,8 +2455,10 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
                info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale;
        }
 
-       if (tp->ecn_flags&TCP_ECN_OK)
+       if (tp->ecn_flags & TCP_ECN_OK)
                info->tcpi_options |= TCPI_OPT_ECN;
+       if (tp->ecn_flags & TCP_ECN_SEEN)
+               info->tcpi_options |= TCPI_OPT_ECN_SEEN;
 
        info->tcpi_rto = jiffies_to_usecs(icsk->icsk_rto);
        info->tcpi_ato = jiffies_to_usecs(icsk->icsk_ack.ato);