Merge branch 'mptcp-mib-counters'

Matthieu Baerts says:

====================
mptcp: add CurrEstab MIB counter

This MIB counter is similar to the one of TCP -- CurrEstab -- available
in /proc/net/snmp. This is useful to quickly list the number of MPTCP
connections without having to iterate over all of them.

Patch 1 prepares its support by adding new helper functions:

 - MPTCP_DEC_STATS(): similar to MPTCP_INC_STATS(), but this time to
   decrement a counter.

 - mptcp_set_state(): similar to tcp_set_state(), to change the state of
   an MPTCP socket, and to inc/decrement the new counter when needed.

Patch 2 uses mptcp_set_state() instead of directly calling
inet_sk_state_store() to change the state of MPTCP sockets.

Patch 3 and 4 validate the new feature in MPTCP "join" and "diag"
selftests.
====================
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/mib.c

@@ -66,6 +66,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {
 	SNMP_MIB_ITEM("RcvWndShared", MPTCP_MIB_RCVWNDSHARED),
 	SNMP_MIB_ITEM("RcvWndConflictUpdate", MPTCP_MIB_RCVWNDCONFLICTUPDATE),
 	SNMP_MIB_ITEM("RcvWndConflict", MPTCP_MIB_RCVWNDCONFLICT),
+	SNMP_MIB_ITEM("MPCurrEstab", MPTCP_MIB_CURRESTAB),
 	SNMP_MIB_SENTINEL
 };
 

net/mptcp/mib.h

@@ -65,6 +65,7 @@ enum linux_mptcp_mib_field {
 					 * conflict with another subflow while updating msk rcv wnd
 					 */
 	MPTCP_MIB_RCVWNDCONFLICT,	/* Conflict with while updating msk rcv wnd */
+	MPTCP_MIB_CURRESTAB,		/* Current established MPTCP connections */
 	__MPTCP_MIB_MAX
 };
 
@@ -95,4 +96,11 @@ static inline void __MPTCP_INC_STATS(struct net *net,
 		__SNMP_INC_STATS(net->mib.mptcp_statistics, field);
 }
 
+static inline void MPTCP_DEC_STATS(struct net *net,
+				   enum linux_mptcp_mib_field field)
+{
+	if (likely(net->mib.mptcp_statistics))
+		SNMP_DEC_STATS(net->mib.mptcp_statistics, field);
+}
+
 bool mptcp_mib_alloc(struct net *net);

net/mptcp/pm_netlink.c

@@ -1048,6 +1048,11 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
 	if (err)
 		return err;
 
+	/* We don't use mptcp_set_state() here because it needs to be called
+	 * under the msk socket lock. For the moment, that will not bring
+	 * anything more than only calling inet_sk_state_store(), because the
+	 * old status is known (TCP_CLOSE).
+	 */
 	inet_sk_state_store(newsk, TCP_LISTEN);
 	lock_sock(ssk);
 	err = __inet_listen_sk(ssk, backlog);

net/mptcp/protocol.c

@@ -429,11 +429,11 @@ static void mptcp_check_data_fin_ack(struct sock *sk)
 
 		switch (sk->sk_state) {
 		case TCP_FIN_WAIT1:
-			inet_sk_state_store(sk, TCP_FIN_WAIT2);
+			mptcp_set_state(sk, TCP_FIN_WAIT2);
 			break;
 		case TCP_CLOSING:
 		case TCP_LAST_ACK:
-			inet_sk_state_store(sk, TCP_CLOSE);
+			mptcp_set_state(sk, TCP_CLOSE);
 			break;
 		}
 
@@ -594,13 +594,13 @@ static bool mptcp_check_data_fin(struct sock *sk)
 
 		switch (sk->sk_state) {
 		case TCP_ESTABLISHED:
-			inet_sk_state_store(sk, TCP_CLOSE_WAIT);
+			mptcp_set_state(sk, TCP_CLOSE_WAIT);
 			break;
 		case TCP_FIN_WAIT1:
-			inet_sk_state_store(sk, TCP_CLOSING);
+			mptcp_set_state(sk, TCP_CLOSING);
 			break;
 		case TCP_FIN_WAIT2:
-			inet_sk_state_store(sk, TCP_CLOSE);
+			mptcp_set_state(sk, TCP_CLOSE);
 			break;
 		default:
 			/* Other states not expected */
@@ -775,7 +775,7 @@ static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)
 	 */
 	ssk_state = inet_sk_state_load(ssk);
 	if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
-		inet_sk_state_store(sk, ssk_state);
+		mptcp_set_state(sk, ssk_state);
 	WRITE_ONCE(sk->sk_err, -err);
 
 	/* This barrier is coupled with smp_rmb() in mptcp_poll() */
@@ -2463,7 +2463,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 	    inet_sk_state_load(msk->first) == TCP_CLOSE) {
 		if (sk->sk_state != TCP_ESTABLISHED ||
 		    msk->in_accept_queue || sock_flag(sk, SOCK_DEAD)) {
-			inet_sk_state_store(sk, TCP_CLOSE);
+			mptcp_set_state(sk, TCP_CLOSE);
 			mptcp_close_wake_up(sk);
 		} else {
 			mptcp_start_tout_timer(sk);
@@ -2558,7 +2558,7 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 		WRITE_ONCE(sk->sk_err, ECONNRESET);
 	}
 
-	inet_sk_state_store(sk, TCP_CLOSE);
+	mptcp_set_state(sk, TCP_CLOSE);
 	WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK);
 	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
 	set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
@@ -2693,7 +2693,7 @@ static void mptcp_do_fastclose(struct sock *sk)
 	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	inet_sk_state_store(sk, TCP_CLOSE);
+	mptcp_set_state(sk, TCP_CLOSE);
 	mptcp_for_each_subflow_safe(msk, subflow, tmp)
 		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow),
 				  subflow, MPTCP_CF_FASTCLOSE);
@@ -2871,6 +2871,24 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
 	release_sock(ssk);
 }
 
+void mptcp_set_state(struct sock *sk, int state)
+{
+	int oldstate = sk->sk_state;
+
+	switch (state) {
+	case TCP_ESTABLISHED:
+		if (oldstate != TCP_ESTABLISHED)
+			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB);
+		break;
+
+	default:
+		if (oldstate == TCP_ESTABLISHED)
+			MPTCP_DEC_STATS(sock_net(sk), MPTCP_MIB_CURRESTAB);
+	}
+
+	inet_sk_state_store(sk, state);
+}
+
 static const unsigned char new_state[16] = {
 	/* current state:     new state:      action:	*/
 	[0 /* (Invalid) */] = TCP_CLOSE,
@@ -2893,7 +2911,7 @@ static int mptcp_close_state(struct sock *sk)
 	int next = (int)new_state[sk->sk_state];
 	int ns = next & TCP_STATE_MASK;
 
-	inet_sk_state_store(sk, ns);
+	mptcp_set_state(sk, ns);
 
 	return next & TCP_ACTION_FIN;
 }
@@ -3004,7 +3022,7 @@ bool __mptcp_close(struct sock *sk, long timeout)
 
 	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE)) {
 		mptcp_check_listen_stop(sk);
-		inet_sk_state_store(sk, TCP_CLOSE);
+		mptcp_set_state(sk, TCP_CLOSE);
 		goto cleanup;
 	}
 
@@ -3047,7 +3065,7 @@ bool __mptcp_close(struct sock *sk, long timeout)
 	 * state, let's not keep resources busy for no reasons
 	 */
 	if (subflows_alive == 0)
-		inet_sk_state_store(sk, TCP_CLOSE);
+		mptcp_set_state(sk, TCP_CLOSE);
 
 	sock_hold(sk);
 	pr_debug("msk=%p state=%d", sk, sk->sk_state);
@@ -3113,7 +3131,7 @@ static int mptcp_disconnect(struct sock *sk, int flags)
 		return -EBUSY;
 
 	mptcp_check_listen_stop(sk);
-	inet_sk_state_store(sk, TCP_CLOSE);
+	mptcp_set_state(sk, TCP_CLOSE);
 
 	mptcp_stop_rtx_timer(sk);
 	mptcp_stop_tout_timer(sk);
@@ -3201,7 +3219,7 @@ struct sock *mptcp_sk_clone_init(const struct sock *sk,
 	/* this can't race with mptcp_close(), as the msk is
 	 * not yet exposted to user-space
 	 */
-	inet_sk_state_store(nsk, TCP_ESTABLISHED);
+	mptcp_set_state(nsk, TCP_ESTABLISHED);
 
 	/* The msk maintain a ref to each subflow in the connections list */
 	WRITE_ONCE(msk->first, ssk);
@@ -3622,7 +3640,7 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	if (IS_ERR(ssk))
 		return PTR_ERR(ssk);
 
-	inet_sk_state_store(sk, TCP_SYN_SENT);
+	mptcp_set_state(sk, TCP_SYN_SENT);
 	subflow = mptcp_subflow_ctx(ssk);
 #ifdef CONFIG_TCP_MD5SIG
 	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
@@ -3672,7 +3690,7 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	if (unlikely(err)) {
 		/* avoid leaving a dangling token in an unconnected socket */
 		mptcp_token_destroy(msk);
-		inet_sk_state_store(sk, TCP_CLOSE);
+		mptcp_set_state(sk, TCP_CLOSE);
 		return err;
 	}
 
@@ -3761,13 +3779,13 @@ static int mptcp_listen(struct socket *sock, int backlog)
 		goto unlock;
 	}
 
-	inet_sk_state_store(sk, TCP_LISTEN);
+	mptcp_set_state(sk, TCP_LISTEN);
 	sock_set_flag(sk, SOCK_RCU_FREE);
 
 	lock_sock(ssk);
 	err = __inet_listen_sk(ssk, backlog);
 	release_sock(ssk);
-	inet_sk_state_store(sk, inet_sk_state_load(ssk));
+	mptcp_set_state(sk, inet_sk_state_load(ssk));
 
 	if (!err) {
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
@@ -3845,7 +3863,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 			__mptcp_close_ssk(newsk, msk->first,
 					  mptcp_subflow_ctx(msk->first), 0);
 			if (unlikely(list_is_singular(&msk->conn_list)))
-				inet_sk_state_store(newsk, TCP_CLOSE);
+				mptcp_set_state(newsk, TCP_CLOSE);
 		}
 	} else {
 		MPTCP_INC_STATS(sock_net(ssk),

net/mptcp/protocol.h

@@ -641,6 +641,7 @@ bool __mptcp_close(struct sock *sk, long timeout);
 void mptcp_cancel_work(struct sock *sk);
 void __mptcp_unaccepted_force_close(struct sock *sk);
 void mptcp_set_owner_r(struct sk_buff *skb, struct sock *sk);
+void mptcp_set_state(struct sock *sk, int state);
 
 bool mptcp_addresses_equal(const struct mptcp_addr_info *a,
 			   const struct mptcp_addr_info *b, bool use_port);

net/mptcp/subflow.c

@@ -425,7 +425,7 @@ void __mptcp_sync_state(struct sock *sk, int state)
 
 	__mptcp_propagate_sndbuf(sk, msk->first);
 	if (sk->sk_state == TCP_SYN_SENT) {
-		inet_sk_state_store(sk, state);
+		mptcp_set_state(sk, state);
 		sk->sk_state_change(sk);
 	}
 }

tools/testing/selftests/net/mptcp/diag.sh

@@ -56,7 +56,7 @@ __chk_nr()
 	local command="$1"
 	local expected=$2
 	local msg="$3"
-	local skip="${4:-SKIP}"
+	local skip="${4-SKIP}"
 	local nr
 
 	nr=$(eval $command)
@@ -182,6 +182,15 @@ chk_msk_inuse()
 	__chk_nr get_msk_inuse $expected "$msg" 0
 }
 
+# $1: cestab nr
+chk_msk_cestab()
+{
+	local cestab=$1
+
+	__chk_nr "mptcp_lib_get_counter ${ns} MPTcpExtMPCurrEstab" \
+		 "${cestab}" "....chk ${cestab} cestab" ""
+}
+
 wait_connected()
 {
 	local listener_ns="${1}"
@@ -219,9 +228,11 @@ chk_msk_nr 2 "after MPC handshake "
 chk_msk_remote_key_nr 2 "....chk remote_key"
 chk_msk_fallback_nr 0 "....chk no fallback"
 chk_msk_inuse 2 "....chk 2 msk in use"
+chk_msk_cestab 2
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab 0
 
 echo "a" | \
 	timeout ${timeout_test} \
@@ -237,9 +248,11 @@ echo "b" | \
 wait_connected $ns 10001
 chk_msk_fallback_nr 1 "check fallback"
 chk_msk_inuse 1 "....chk 1 msk in use"
+chk_msk_cestab 1
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab 0
 
 NR_CLIENTS=100
 for I in `seq 1 $NR_CLIENTS`; do
@@ -261,9 +274,11 @@ done
 
 wait_msk_nr $((NR_CLIENTS*2)) "many msk socket present"
 chk_msk_inuse $((NR_CLIENTS*2)) "....chk many msk in use"
+chk_msk_cestab $((NR_CLIENTS*2))
 flush_pids
 
 chk_msk_inuse 0 "....chk 0 msk in use after flush"
+chk_msk_cestab 0
 
 mptcp_lib_result_print_all_tap
 exit $ret

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -56,6 +56,8 @@ unset FAILING_LINKS
 unset test_linkfail
 unset addr_nr_ns1
 unset addr_nr_ns2
+unset cestab_ns1
+unset cestab_ns2
 unset sflags
 unset fastclose
 unset fullmesh
@@ -976,6 +978,34 @@ pm_nl_set_endpoint()
 	fi
 }
 
+chk_cestab_nr()
+{
+	local ns=$1
+	local cestab=$2
+	local count
+
+	print_check "cestab $cestab"
+	count=$(mptcp_lib_get_counter ${ns} "MPTcpExtMPCurrEstab")
+	if [ -z "$count" ]; then
+		print_skip
+	elif [ "$count" != "$cestab" ]; then
+		fail_test "got $count current establish[s] expected $cestab"
+	else
+		print_ok
+	fi
+}
+
+# $1 namespace 1, $2 namespace 2
+check_cestab()
+{
+	if [ -n "${cestab_ns1}" ]; then
+		chk_cestab_nr ${1} ${cestab_ns1}
+	fi
+	if [ -n "${cestab_ns2}" ]; then
+		chk_cestab_nr ${2} ${cestab_ns2}
+	fi
+}
+
 do_transfer()
 {
 	local listener_ns="$1"
@@ -1089,6 +1119,7 @@ do_transfer()
 	local cpid=$!
 
 	pm_nl_set_endpoint $listener_ns $connector_ns $connect_addr
+	check_cestab $listener_ns $connector_ns
 
 	wait $cpid
 	local retc=$?
@@ -2477,47 +2508,52 @@ add_tests()
 	if reset "add single subflow"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 0 1
-		addr_nr_ns2=1 speed=slow \
+		addr_nr_ns2=1 speed=slow cestab_ns2=1 \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 1
+		chk_cestab_nr $ns2 0
 	fi
 
 	# add signal address
 	if reset "add signal address"; then
 		pm_nl_set_limits $ns1 0 1
 		pm_nl_set_limits $ns2 1 1
-		addr_nr_ns1=1 speed=slow \
+		addr_nr_ns1=1 speed=slow cestab_ns1=1 \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 1 1 1
 		chk_add_nr 1 1
+		chk_cestab_nr $ns1 0
 	fi
 
 	# add multiple subflows
 	if reset "add multiple subflows"; then
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
-		addr_nr_ns2=2 speed=slow \
+		addr_nr_ns2=2 speed=slow cestab_ns2=1 \
 			run_tests $ns1 $ns2 10.0.1.1
 		chk_join_nr 2 2 2
+		chk_cestab_nr $ns2 0
 	fi
 
 	# add multiple subflows IPv6
 	if reset "add multiple subflows IPv6"; then
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 0 2
-		addr_nr_ns2=2 speed=slow \
+		addr_nr_ns2=2 speed=slow cestab_ns2=1 \
 			run_tests $ns1 $ns2 dead:beef:1::1
 		chk_join_nr 2 2 2
+		chk_cestab_nr $ns2 0
 	fi
 
 	# add multiple addresses IPv6
 	if reset "add multiple addresses IPv6"; then
 		pm_nl_set_limits $ns1 0 2
 		pm_nl_set_limits $ns2 2 2
-		addr_nr_ns1=2 speed=slow \
+		addr_nr_ns1=2 speed=slow cestab_ns1=1 \
 			run_tests $ns1 $ns2 dead:beef:1::1
 		chk_join_nr 2 2 2
 		chk_add_nr 2 2
+		chk_cestab_nr $ns1 0
 	fi
 }