Merge branch 'mptcp-fastclose'

Mat Martineau says:

====================
mptcp: Fastclose edge cases and error handling

MPTCP has existing code to use the MP_FASTCLOSE option header, which
works like a RST for the MPTCP-level connection (regular RSTs only
affect specific subflows in MPTCP). This series has some improvements
for fastclose.

Patch 1 aligns fastclose socket error handling with TCP RST behavior on
TCP sockets.

Patch 2 adds use of MP_FASTCLOSE in some more edge cases, like file
descriptor close, FIN_WAIT timeout, and when the socket has unread data.

Patch 3 updates the fastclose self tests.

Patch 4 does not change any code, just fixes some outdated comments.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 217 insertions, 62 deletions

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 760404b15cd0..f599ad44ed24 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -662,9 +662,9 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 
 		skb = skb_peek(&ssk->sk_receive_queue);
 		if (!skb) {
-			/* if no data is found, a racing workqueue/recvmsg
-			 * already processed the new data, stop here or we
-			 * can enter an infinite loop
+			/* With racing move_skbs_to_msk() and __mptcp_move_skbs(),
+			 * a different CPU can have already processed the pending
+			 * data, stop here or we can enter an infinite loop
 			 */
 			if (!moved)
 				done = true;
@@ -672,9 +672,9 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 		}
 
 		if (__mptcp_check_fallback(msk)) {
-			/* if we are running under the workqueue, TCP could have
-			 * collapsed skbs between dummy map creation and now
-			 * be sure to adjust the size
+			/* Under fallback skbs have no MPTCP extension and TCP could
+			 * collapse them between the dummy map creation and the
+			 * current dequeue. Be sure to adjust the map size.
 			 */
 			map_remaining = skb->len;
 			subflow->map_data_len = skb->len;
@@ -1707,7 +1707,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 			goto out;
 		} else if (ret) {
 			release_sock(ssk);
-			goto out;
+			goto do_error;
 		}
 		release_sock(ssk);
 	}
@@ -1717,9 +1717,13 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
 		ret = sk_stream_wait_connect(sk, &timeo);
 		if (ret)
-			goto out;
+			goto do_error;
 	}
 
+	ret = -EPIPE;
+	if (unlikely(sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)))
+		goto do_error;
+
 	pfrag = sk_page_frag(sk);
 
 	while (msg_data_left(msg)) {
@@ -1728,11 +1732,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		bool dfrag_collapsed;
 		size_t psize, offset;
 
-		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
-			ret = -EPIPE;
-			goto out;
-		}
-
 		/* reuse tail pfrag, if possible, or carve a new one from the
 		 * page allocator
 		 */
@@ -1764,7 +1763,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		if (copy_page_from_iter(dfrag->page, offset, psize,
 					&msg->msg_iter) != psize) {
 			ret = -EFAULT;
-			goto out;
+			goto do_error;
 		}
 
 		/* data successfully copied into the write queue */
@@ -1796,7 +1795,7 @@ wait_for_memory:
 		__mptcp_push_pending(sk, msg->msg_flags);
 		ret = sk_stream_wait_memory(sk, &timeo);
 		if (ret)
-			goto out;
+			goto do_error;
 	}
 
 	if (copied)
@@ -1804,7 +1803,14 @@ wait_for_memory:
 
 out:
 	release_sock(sk);
-	return copied ? : ret;
+	return copied;
+
+do_error:
+	if (copied)
+		goto out;
+
+	copied = sk_stream_error(sk, msg->msg_flags, ret);
+	goto out;
 }
 
 static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
@@ -2307,8 +2313,14 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 
 	lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
 
-	if (flags & MPTCP_CF_FASTCLOSE)
+	if (flags & MPTCP_CF_FASTCLOSE) {
+		/* be sure to force the tcp_disconnect() path,
+		 * to generate the egress reset
+		 */
+		ssk->sk_lingertime = 0;
+		sock_set_flag(ssk, SOCK_LINGER);
 		subflow->send_fastclose = 1;
+	}
 
 	need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
 	if (!dispose_it) {
@@ -2441,12 +2453,31 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 		unlock_sock_fast(tcp_sk, slow);
 	}
 
+	/* Mirror the tcp_reset() error propagation */
+	switch (sk->sk_state) {
+	case TCP_SYN_SENT:
+		sk->sk_err = ECONNREFUSED;
+		break;
+	case TCP_CLOSE_WAIT:
+		sk->sk_err = EPIPE;
+		break;
+	case TCP_CLOSE:
+		return;
+	default:
+		sk->sk_err = ECONNRESET;
+	}
+
 	inet_sk_state_store(sk, TCP_CLOSE);
 	sk->sk_shutdown = SHUTDOWN_MASK;
 	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
 	set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
 
-	mptcp_close_wake_up(sk);
+	/* the calling mptcp_worker will properly destroy the socket */
+	if (sock_flag(sk, SOCK_DEAD))
+		return;
+
+	sk->sk_state_change(sk);
+	sk_error_report(sk);
 }
 
 static void __mptcp_retrans(struct sock *sk)
@@ -2552,6 +2583,16 @@ static void mptcp_mp_fail_no_response(struct mptcp_sock *msk)
 	mptcp_reset_timeout(msk, 0);
 }
 
+static void mptcp_do_fastclose(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow, *tmp;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow_safe(msk, subflow, tmp)
+		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow),
+				  subflow, MPTCP_CF_FASTCLOSE);
+}
+
 static void mptcp_worker(struct work_struct *work)
 {
 	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
@@ -2580,11 +2621,15 @@ static void mptcp_worker(struct work_struct *work)
 	 * closed, but we need the msk around to reply to incoming DATA_FIN,
 	 * even if it is orphaned and in FIN_WAIT2 state
 	 */
-	if (sock_flag(sk, SOCK_DEAD) &&
-	    (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {
-		inet_sk_state_store(sk, TCP_CLOSE);
-		__mptcp_destroy_sock(sk);
-		goto unlock;
+	if (sock_flag(sk, SOCK_DEAD)) {
+		if (mptcp_check_close_timeout(sk)) {
+			inet_sk_state_store(sk, TCP_CLOSE);
+			mptcp_do_fastclose(sk);
+		}
+		if (sk->sk_state == TCP_CLOSE) {
+			__mptcp_destroy_sock(sk);
+			goto unlock;
+		}
 	}
 
 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
@@ -2825,6 +2870,18 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sock_put(sk);
 }
 
+static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
+{
+	/* Concurrent splices from sk_receive_queue into receive_queue will
+	 * always show at least one non-empty queue when checked in this order.
+	 */
+	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&
+	    skb_queue_empty_lockless(&msk->receive_queue))
+		return 0;
+
+	return EPOLLIN | EPOLLRDNORM;
+}
+
 bool __mptcp_close(struct sock *sk, long timeout)
 {
 	struct mptcp_subflow_context *subflow;
@@ -2838,8 +2895,13 @@ bool __mptcp_close(struct sock *sk, long timeout)
 		goto cleanup;
 	}
 
-	if (mptcp_close_state(sk))
+	if (mptcp_check_readable(msk)) {
+		/* the msk has read data, do the MPTCP equivalent of TCP reset */
+		inet_sk_state_store(sk, TCP_CLOSE);
+		mptcp_do_fastclose(sk);
+	} else if (mptcp_close_state(sk)) {
 		__mptcp_wr_shutdown(sk);
+	}
 
 	sk_stream_wait_close(sk, timeout);
 
@@ -3656,18 +3718,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 	return err;
 }
 
-static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
-{
-	/* Concurrent splices from sk_receive_queue into receive_queue will
-	 * always show at least one non-empty queue when checked in this order.
-	 */
-	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&
-	    skb_queue_empty_lockless(&msk->receive_queue))
-		return 0;
-
-	return EPOLLIN | EPOLLRDNORM;
-}
-
 static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
 {
 	struct sock *sk = (struct sock *)msk;
@@ -3718,7 +3768,7 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
 
-	/* This barrier is coupled with smp_wmb() in tcp_reset() */
+	/* This barrier is coupled with smp_wmb() in __mptcp_error_report() */
 	smp_rmb();
 	if (sk->sk_err)
 		mask |= EPOLLERR;
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
index 24d4e9cb617e..e54653ea2ed4 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
@@ -72,6 +72,8 @@ static int cfg_wait;
 static uint32_t cfg_mark;
 static char *cfg_input;
 static int cfg_repeat = 1;
+static int cfg_truncate;
+static int cfg_rcv_trunc;
 
 struct cfg_cmsg_types {
 	unsigned int cmsg_enabled:1;
@@ -95,11 +97,15 @@ static struct cfg_sockopt_types cfg_sockopt_types;
 
 static void die_usage(void)
 {
-	fprintf(stderr, "Usage: mptcp_connect [-6] [-c cmsg] [-i file] [-I num] [-j] [-l] "
+	fprintf(stderr, "Usage: mptcp_connect [-6] [-c cmsg] [-f offset] [-i file] [-I num] [-j] [-l] "
 		"[-m mode] [-M mark] [-o option] [-p port] [-P mode] [-j] [-l] [-r num] "
 		"[-s MPTCP|TCP] [-S num] [-r num] [-t num] [-T num] [-u] [-w sec] connect_address\n");
 	fprintf(stderr, "\t-6 use ipv6\n");
 	fprintf(stderr, "\t-c cmsg -- test cmsg type <cmsg>\n");
+	fprintf(stderr, "\t-f offset -- stop the I/O after receiving and sending the specified amount "
+		"of bytes. If there are unread bytes in the receive queue, that will cause a MPTCP "
+		"fastclose at close/shutdown. If offset is negative, expect the peer to close before "
+		"all the local data as been sent, thus toleration errors on write and EPIPE signals\n");
 	fprintf(stderr, "\t-i file -- read the data to send from the given file instead of stdin");
 	fprintf(stderr, "\t-I num -- repeat the transfer 'num' times. In listen mode accepts num "
 		"incoming connections, in client mode, disconnect and reconnect to the server\n");
@@ -382,7 +388,7 @@ static size_t do_rnd_write(const int fd, char *buf, const size_t len)
 
 	bw = write(fd, buf, do_w);
 	if (bw < 0)
-		perror("write");
+		return bw;
 
 	/* let the join handshake complete, before going on */
 	if (cfg_join && first) {
@@ -571,7 +577,7 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 		.fd = peerfd,
 		.events = POLLIN | POLLOUT,
 	};
-	unsigned int woff = 0, wlen = 0;
+	unsigned int woff = 0, wlen = 0, total_wlen = 0, total_rlen = 0;
 	char wbuf[8192];
 
 	set_nonblock(peerfd, true);
@@ -597,7 +603,16 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 		}
 
 		if (fds.revents & POLLIN) {
-			len = do_rnd_read(peerfd, rbuf, sizeof(rbuf));
+			ssize_t rb = sizeof(rbuf);
+
+			/* limit the total amount of read data to the trunc value*/
+			if (cfg_truncate > 0) {
+				if (rb + total_rlen > cfg_truncate)
+					rb = cfg_truncate - total_rlen;
+				len = read(peerfd, rbuf, rb);
+			} else {
+				len = do_rnd_read(peerfd, rbuf, sizeof(rbuf));
+			}
 			if (len == 0) {
 				/* no more data to receive:
 				 * peer has closed its write side
@@ -612,10 +627,13 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 
 			/* Else, still have data to transmit */
 			} else if (len < 0) {
+				if (cfg_rcv_trunc)
+					return 0;
 				perror("read");
 				return 3;
 			}
 
+			total_rlen += len;
 			do_write(outfd, rbuf, len);
 		}
 
@@ -628,12 +646,21 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 			if (wlen > 0) {
 				ssize_t bw;
 
+				/* limit the total amount of written data to the trunc value */
+				if (cfg_truncate > 0 && wlen + total_wlen > cfg_truncate)
+					wlen = cfg_truncate - total_wlen;
+
 				bw = do_rnd_write(peerfd, wbuf + woff, wlen);
-				if (bw < 0)
+				if (bw < 0) {
+					if (cfg_rcv_trunc)
+						return 0;
+					perror("write");
 					return 111;
+				}
 
 				woff += bw;
 				wlen -= bw;
+				total_wlen += bw;
 			} else if (wlen == 0) {
 				/* We have no more data to send. */
 				fds.events &= ~POLLOUT;
@@ -652,10 +679,16 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 		}
 
 		if (fds.revents & (POLLERR | POLLNVAL)) {
+			if (cfg_rcv_trunc)
+				return 0;
 			fprintf(stderr, "Unexpected revents: "
 				"POLLERR/POLLNVAL(%x)\n", fds.revents);
 			return 5;
 		}
+
+		if (cfg_truncate > 0 && total_wlen >= cfg_truncate &&
+		    total_rlen >= cfg_truncate)
+			break;
 	}
 
 	/* leave some time for late join/announce */
@@ -1160,11 +1193,13 @@ again:
 	}
 
 	/* close the client socket open only if we are not going to reconnect */
-	ret = copyfd_io(fd_in, fd, 1, cfg_repeat == 1);
+	ret = copyfd_io(fd_in, fd, 1, 0);
 	if (ret)
 		return ret;
 
-	if (--cfg_repeat > 0) {
+	if (cfg_truncate > 0) {
+		xdisconnect(fd, peer->ai_addrlen);
+	} else if (--cfg_repeat > 0) {
 		xdisconnect(fd, peer->ai_addrlen);
 
 		/* the socket could be unblocking at this point, we need the
@@ -1176,7 +1211,10 @@ again:
 		if (cfg_input)
 			close(fd_in);
 		goto again;
+	} else {
+		close(fd);
 	}
+
 	return 0;
 }
 
@@ -1262,8 +1300,19 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "6c:hi:I:jlm:M:o:p:P:r:R:s:S:t:T:w:")) != -1) {
+	while ((c = getopt(argc, argv, "6c:f:hi:I:jlm:M:o:p:P:r:R:s:S:t:T:w:")) != -1) {
 		switch (c) {
+		case 'f':
+			cfg_truncate = atoi(optarg);
+
+			/* when receiving a fastclose, ignore PIPE signals and
+			 * all the I/O errors later in the code
+			 */
+			if (cfg_truncate < 0) {
+				cfg_rcv_trunc = true;
+				signal(SIGPIPE, handle_signal);
+			}
+			break;
 		case 'j':
 			cfg_join = true;
 			cfg_mode = CFG_MODE_POLL;
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 2957fe414639..f3dd5f2a0272 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -346,10 +346,21 @@ check_transfer()
 	local in=$1
 	local out=$2
 	local what=$3
+	local bytes=$4
 	local i a b
 
 	local line
-	cmp -l "$in" "$out" | while read -r i a b; do
+	if [ -n "$bytes" ]; then
+		# when truncating we must check the size explicitly
+		local out_size=$(wc -c $out | awk '{print $1}')
+		if [ $out_size -ne $bytes ]; then
+			echo "[ FAIL ] $what output file has wrong size ($out_size, $bytes)"
+			fail_test
+			return 1
+		fi
+		bytes="--bytes=${bytes}"
+	fi
+	cmp -l "$in" "$out" ${bytes} | while read -r i a b; do
 		local sum=$((0${a} + 0${b}))
 		if [ $check_invert -eq 0 ] || [ $sum -ne $((0xff)) ]; then
 			echo "[ FAIL ] $what does not match (in, out):"
@@ -707,9 +718,31 @@ do_transfer()
 	fi
 
 	local flags="subflow"
+	local extra_cl_args=""
+	local extra_srv_args=""
+	local trunc_size=""
 	if [[ "${addr_nr_ns2}" = "fastclose_"* ]]; then
+		if [ ${test_link_fail} -le 1 ]; then
+			echo "fastclose tests need test_link_fail argument"
+			fail_test
+			return 1
+		fi
+
 		# disconnect
-		extra_args="$extra_args -I ${addr_nr_ns2:10}"
+		trunc_size=${test_link_fail}
+		local side=${addr_nr_ns2:10}
+
+		if [ ${side} = "client" ]; then
+			extra_cl_args="-f ${test_link_fail}"
+			extra_srv_args="-f -1"
+		elif [ ${side} = "server" ]; then
+			extra_srv_args="-f ${test_link_fail}"
+			extra_cl_args="-f -1"
+		else
+			echo "wrong/unknown fastclose spec ${side}"
+			fail_test
+			return 1
+		fi
 		addr_nr_ns2=0
 	elif [[ "${addr_nr_ns2}" = "userspace_"* ]]; then
 		userspace_pm=1
@@ -737,39 +770,41 @@ do_transfer()
 		local_addr="0.0.0.0"
 	fi
 
+	extra_srv_args="$extra_args $extra_srv_args"
 	if [ "$test_link_fail" -gt 1 ];then
 		timeout ${timeout_test} \
 			ip netns exec ${listener_ns} \
 				./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-					$extra_args ${local_addr} < "$sinfail" > "$sout" &
+					$extra_srv_args ${local_addr} < "$sinfail" > "$sout" &
 	else
 		timeout ${timeout_test} \
 			ip netns exec ${listener_ns} \
 				./mptcp_connect -t ${timeout_poll} -l -p $port -s ${srv_proto} \
-					$extra_args ${local_addr} < "$sin" > "$sout" &
+					$extra_srv_args ${local_addr} < "$sin" > "$sout" &
 	fi
 	local spid=$!
 
 	wait_local_port_listen "${listener_ns}" "${port}"
 
+	extra_cl_args="$extra_args $extra_cl_args"
 	if [ "$test_link_fail" -eq 0 ];then
 		timeout ${timeout_test} \
 			ip netns exec ${connector_ns} \
 				./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-					$extra_args $connect_addr < "$cin" > "$cout" &
+					$extra_cl_args $connect_addr < "$cin" > "$cout" &
 	elif [ "$test_link_fail" -eq 1 ] || [ "$test_link_fail" -eq 2 ];then
 		( cat "$cinfail" ; sleep 2; link_failure $listener_ns ; cat "$cinfail" ) | \
 			tee "$cinsent" | \
 			timeout ${timeout_test} \
 				ip netns exec ${connector_ns} \
 					./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-						$extra_args $connect_addr > "$cout" &
+						$extra_cl_args $connect_addr > "$cout" &
 	else
 		tee "$cinsent" < "$cinfail" | \
 			timeout ${timeout_test} \
 				ip netns exec ${connector_ns} \
 					./mptcp_connect -t ${timeout_poll} -p $port -s ${cl_proto} \
-						$extra_args $connect_addr > "$cout" &
+						$extra_cl_args $connect_addr > "$cout" &
 	fi
 	local cpid=$!
 
@@ -971,15 +1006,15 @@ do_transfer()
 	fi
 
 	if [ "$test_link_fail" -gt 1 ];then
-		check_transfer $sinfail $cout "file received by client"
+		check_transfer $sinfail $cout "file received by client" $trunc_size
 	else
-		check_transfer $sin $cout "file received by client"
+		check_transfer $sin $cout "file received by client" $trunc_size
 	fi
 	retc=$?
 	if [ "$test_link_fail" -eq 0 ];then
-		check_transfer $cin $sout "file received by server"
+		check_transfer $cin $sout "file received by server" $trunc_size
 	else
-		check_transfer $cinsent $sout "file received by server"
+		check_transfer $cinsent $sout "file received by server" $trunc_size
 	fi
 	rets=$?
 
@@ -1188,12 +1223,23 @@ chk_fclose_nr()
 {
 	local fclose_tx=$1
 	local fclose_rx=$2
+	local ns_invert=$3
 	local count
 	local dump_stats
+	local ns_tx=$ns2
+	local ns_rx=$ns1
+	local extra_msg="   "
+
+	if [[ $ns_invert = "invert" ]]; then
+		ns_tx=$ns1
+		ns_rx=$ns2
+		extra_msg=${extra_msg}"invert"
+	fi
 
 	printf "%-${nr_blank}s %s" " " "ctx"
-	count=$(ip netns exec $ns2 nstat -as | grep MPTcpExtMPFastcloseTx | awk '{print $2}')
+	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPFastcloseTx | awk '{print $2}')
 	[ -z "$count" ] && count=0
+	[ "$count" != "$fclose_tx" ] && extra_msg="$extra_msg,tx=$count"
 	if [ "$count" != "$fclose_tx" ]; then
 		echo "[fail] got $count MP_FASTCLOSE[s] TX expected $fclose_tx"
 		fail_test
@@ -1203,17 +1249,20 @@ chk_fclose_nr()
 	fi
 
 	echo -n " - fclzrx"
-	count=$(ip netns exec $ns1 nstat -as | grep MPTcpExtMPFastcloseRx | awk '{print $2}')
+	count=$(ip netns exec $ns_rx nstat -as | grep MPTcpExtMPFastcloseRx | awk '{print $2}')
 	[ -z "$count" ] && count=0
+	[ "$count" != "$fclose_rx" ] && extra_msg="$extra_msg,rx=$count"
 	if [ "$count" != "$fclose_rx" ]; then
 		echo "[fail] got $count MP_FASTCLOSE[s] RX expected $fclose_rx"
 		fail_test
 		dump_stats=1
 	else
-		echo "[ ok ]"
+		echo -n "[ ok ]"
 	fi
 
 	[ "${dump_stats}" = 1 ] && dump_stats
+
+	echo "$extra_msg"
 }
 
 chk_rst_nr()
@@ -1236,7 +1285,7 @@ chk_rst_nr()
 	printf "%-${nr_blank}s %s" " " "rtx"
 	count=$(ip netns exec $ns_tx nstat -as | grep MPTcpExtMPRstTx | awk '{print $2}')
 	[ -z "$count" ] && count=0
-	if [ "$count" != "$rst_tx" ]; then
+	if [ $count -lt $rst_tx ]; then
 		echo "[fail] got $count MP_RST[s] TX expected $rst_tx"
 		fail_test
 		dump_stats=1
@@ -1247,7 +1296,7 @@ chk_rst_nr()
 	echo -n " - rstrx "
 	count=$(ip netns exec $ns_rx nstat -as | grep MPTcpExtMPRstRx | awk '{print $2}')
 	[ -z "$count" ] && count=0
-	if [ "$count" != "$rst_rx" ]; then
+	if [ "$count" -lt "$rst_rx" ]; then
 		echo "[fail] got $count MP_RST[s] RX expected $rst_rx"
 		fail_test
 		dump_stats=1
@@ -2801,11 +2850,18 @@ fullmesh_tests()
 fastclose_tests()
 {
 	if reset "fastclose test"; then
-		run_tests $ns1 $ns2 10.0.1.1 1024 0 fastclose_2
+		run_tests $ns1 $ns2 10.0.1.1 1024 0 fastclose_client
 		chk_join_nr 0 0 0
 		chk_fclose_nr 1 1
 		chk_rst_nr 1 1 invert
 	fi
+
+	if reset "fastclose server test"; then
+		run_tests $ns1 $ns2 10.0.1.1 1024 0 fastclose_server
+		chk_join_nr 0 0 0
+		chk_fclose_nr 1 1 invert
+		chk_rst_nr 1 1
+	fi
 }
 
 pedit_action_pkts()