Merge branch 'mptcp-miscellaneous-fixes-and-a-new-test-case'

Mat Martineau says:

====================
mptcp: Miscellaneous fixes and a new test case

Patches 1 and 3 remove helpers that were iterating over the subflow
connection list without proper locking. Iteration was not needed in
either case.

Patch 2 fixes handling of MP_FAIL timeout, checking for orphaned
subflows instead of using the MPTCP socket data lock and connection
state.

Patch 4 adds a test for MP_FAIL timeout using tc pedit to induce checksum
failures.
====================

Link: https://lore.kernel.org/r/20220518220446.209750-1-mathew.j.martineau@linux.intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/pm.c

@@ -303,7 +303,7 @@ void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
 
 	pr_debug("fail_seq=%llu", fail_seq);
 
-	if (mptcp_has_another_subflow(sk) || !READ_ONCE(msk->allow_infinite_fallback))
+	if (!READ_ONCE(msk->allow_infinite_fallback))
 		return;
 
 	if (!READ_ONCE(subflow->mp_fail_response_expect)) {
@@ -312,13 +312,10 @@ void mptcp_pm_mp_fail_received(struct sock *sk, u64 fail_seq)
 		subflow->send_mp_fail = 1;
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX);
 		subflow->send_infinite_map = 1;
-	} else if (s && inet_sk_state_load(s) != TCP_CLOSE) {
+	} else if (!sock_flag(sk, SOCK_DEAD)) {
 		pr_debug("MP_FAIL response received");
 
-		mptcp_data_lock(s);
-		if (inet_sk_state_load(s) != TCP_CLOSE)
 		sk_stop_timer(s, &s->sk_timer);
-		mptcp_data_unlock(s);
 	}
 }
 

net/mptcp/protocol.c

@@ -2190,23 +2190,10 @@ mp_fail_response_expect_subflow(struct mptcp_sock *msk)
 	return ret;
 }
 
-static void mptcp_check_mp_fail_response(struct mptcp_sock *msk)
-{
-	struct mptcp_subflow_context *subflow;
-	struct sock *sk = (struct sock *)msk;
-
-	bh_lock_sock(sk);
-	subflow = mp_fail_response_expect_subflow(msk);
-	if (subflow)
-		__set_bit(MPTCP_FAIL_NO_RESPONSE, &msk->flags);
-	bh_unlock_sock(sk);
-}
-
 static void mptcp_timeout_timer(struct timer_list *t)
 {
 	struct sock *sk = from_timer(sk, t, sk_timer);
 
-	mptcp_check_mp_fail_response(mptcp_sk(sk));
 	mptcp_schedule_work(sk);
 	sock_put(sk);
 }
@@ -2588,7 +2575,6 @@ static void mptcp_worker(struct work_struct *work)
 	if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
 		__mptcp_retrans(sk);
 
-	if (test_and_clear_bit(MPTCP_FAIL_NO_RESPONSE, &msk->flags))
 	mptcp_mp_fail_no_response(msk);
 
 unlock:

net/mptcp/protocol.h

@@ -117,7 +117,6 @@
 #define MPTCP_WORK_EOF		3
 #define MPTCP_FALLBACK_DONE	4
 #define MPTCP_WORK_CLOSE_SUBFLOW 5
-#define MPTCP_FAIL_NO_RESPONSE	6
 
 /* MPTCP socket release cb flags */
 #define MPTCP_PUSH_PENDING	1
@@ -650,19 +649,6 @@ static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
 	inet_csk(sk)->icsk_af_ops = ctx->icsk_af_ops;
 }
 
-static inline bool mptcp_has_another_subflow(struct sock *ssk)
-{
-	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk), *tmp;
-	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
-
-	mptcp_for_each_subflow(msk, tmp) {
-		if (tmp != subflow)
-			return true;
-	}
-
-	return false;
-}
-
 void __init mptcp_proto_init(void);
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 int __init mptcp_proto_v6_init(void);

net/mptcp/subflow.c

@@ -1016,12 +1016,9 @@ static enum mapping_status get_mapping_status(struct sock *ssk,
 		pr_debug("infinite mapping received");
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
 		subflow->map_data_len = 0;
-		if (sk && inet_sk_state_load(sk) != TCP_CLOSE) {
-			mptcp_data_lock(sk);
-			if (inet_sk_state_load(sk) != TCP_CLOSE)
+		if (!sock_flag(ssk, SOCK_DEAD))
 			sk_stop_timer(sk, &sk->sk_timer);
-			mptcp_data_unlock(sk);
-		}
+
 		return MAPPING_INVALID;
 	}
 
@@ -1233,8 +1230,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
 	if (!__mptcp_check_fallback(msk)) {
 		/* RFC 8684 section 3.7. */
 		if (subflow->send_mp_fail) {
-			if (mptcp_has_another_subflow(ssk) ||
-			    !READ_ONCE(msk->allow_infinite_fallback)) {
+			if (!READ_ONCE(msk->allow_infinite_fallback)) {
 				ssk->sk_err = EBADMSG;
 				tcp_set_state(ssk, TCP_CLOSE);
 				subflow->reset_transient = 0;
@@ -1242,9 +1238,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
 				tcp_send_active_reset(ssk, GFP_ATOMIC);
 				while ((skb = skb_peek(&ssk->sk_receive_queue)))
 					sk_eat_skb(ssk, skb);
-			} else {
+			} else if (!sock_flag(ssk, SOCK_DEAD)) {
 				WRITE_ONCE(subflow->mp_fail_response_expect, true);
-				/* The data lock is acquired in __mptcp_move_skbs() */
 				sk_reset_timer((struct sock *)msk,
 					       &((struct sock *)msk)->sk_timer,
 					       jiffies + TCP_RTO_MAX);

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

@@ -2732,6 +2732,16 @@ fail_tests()
 		chk_join_nr 0 0 0 +1 +0 1 0 1 "$(pedit_action_pkts)"
 		chk_fail_nr 1 -1 invert
 	fi
+
+	# multiple subflows
+	if reset_with_fail "MP_FAIL MP_RST" 2; then
+		tc -n $ns2 qdisc add dev ns2eth1 root netem rate 1mbit delay 5
+		pm_nl_set_limits $ns1 0 1
+		pm_nl_set_limits $ns2 0 1
+		pm_nl_add_endpoint $ns2 10.0.2.2 dev ns2eth2 flags subflow
+		run_tests $ns1 $ns2 10.0.1.1 1024
+		chk_join_nr 1 1 1 1 0 1 1 0 "$(pedit_action_pkts)"
+	fi
 }
 
 userspace_tests()