From: Davide Caratti <[email protected]>
Current MPTCP servers increment MPTcpExtMPCapableFallbackACK when they
accept non-MPC connections. As reported by Christoph, this is "surprising"
because the counter might become greater than MPTcpExtMPCapableSYNRX.
MPTcpExtMPCapableFallbackACK counter's name suggests it should only be
incremented when a connection was seen using MPTCP options, then a
fallback to TCP has been done. Let's do that by incrementing it when
the subflow context of an inbound MPC connection attempt is dropped.
Also, update mptcp_connect.sh kselftest, to ensure that the
above MIB does not increment in case a pure TCP client connects to a
MPTCP server.
Fixes: fc518953bc9c ("mptcp: add and use MIB counter infrastructure")
Cc: [email protected]
Reported-by: Christoph Paasch <[email protected]>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/449
Signed-off-by: Davide Caratti <[email protected]>
Reviewed-by: Mat Martineau <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
---
net/mptcp/protocol.c | 2 --
net/mptcp/subflow.c | 2 ++
tools/testing/selftests/net/mptcp/mptcp_connect.sh | 9 +++++++++
3 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 3a1967bc7bad..7e74b812e366 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3937,8 +3937,6 @@ static int mptcp_stream_accept(struct socket *sock,
struct socket *newsock,
mptcp_set_state(newsk, TCP_CLOSE);
}
} else {
- MPTCP_INC_STATS(sock_net(ssk),
- MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
tcpfallback:
newsk->sk_kern_sock = kern;
lock_sock(newsk);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 1626dd20c68f..6042a47da61b 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -905,6 +905,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock
*sk,
return child;
fallback:
+ if (fallback)
+ SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
mptcp_subflow_drop_ctx(child);
return child;
}
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 4c4248554826..4131f3263a48 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -383,12 +383,14 @@ do_transfer()
local stat_cookierx_last
local stat_csum_err_s
local stat_csum_err_c
+ local stat_tcpfb_last_l
stat_synrx_last_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableSYNRX")
stat_ackrx_last_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableACKRX")
stat_cookietx_last=$(mptcp_lib_get_counter "${listener_ns}"
"TcpExtSyncookiesSent")
stat_cookierx_last=$(mptcp_lib_get_counter "${listener_ns}"
"TcpExtSyncookiesRecv")
stat_csum_err_s=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtDataCsumErr")
stat_csum_err_c=$(mptcp_lib_get_counter "${connector_ns}"
"MPTcpExtDataCsumErr")
+ stat_tcpfb_last_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableFallbackACK")
timeout ${timeout_test} \
ip netns exec ${listener_ns} \
@@ -457,11 +459,13 @@ do_transfer()
local stat_cookietx_now
local stat_cookierx_now
local stat_ooo_now
+ local stat_tcpfb_now_l
stat_synrx_now_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableSYNRX")
stat_ackrx_now_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableACKRX")
stat_cookietx_now=$(mptcp_lib_get_counter "${listener_ns}"
"TcpExtSyncookiesSent")
stat_cookierx_now=$(mptcp_lib_get_counter "${listener_ns}"
"TcpExtSyncookiesRecv")
stat_ooo_now=$(mptcp_lib_get_counter "${listener_ns}"
"TcpExtTCPOFOQueue")
+ stat_tcpfb_now_l=$(mptcp_lib_get_counter "${listener_ns}"
"MPTcpExtMPCapableFallbackACK")
expect_synrx=$((stat_synrx_last_l))
expect_ackrx=$((stat_ackrx_last_l))
@@ -508,6 +512,11 @@ do_transfer()
fi
fi
+ if [ ${stat_ooo_now} -eq 0 ] && [ ${stat_tcpfb_last_l} -ne
${stat_tcpfb_now_l} ]; then
+ mptcp_lib_pr_fail "unexpected fallback to TCP"
+ rets=1
+ fi
+
if [ $cookies -eq 2 ];then
if [ $stat_cookietx_last -ge $stat_cookietx_now ] ;then
extra+=" WARN: CookieSent: did not advance"
--
2.43.0
