1 files changed, 30 insertions, 14 deletions

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 6c448a0be949..88bf092f230a 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -68,6 +68,26 @@ static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk)
 	return &inet_stream_ops;
 }
 
+bool __mptcp_try_fallback(struct mptcp_sock *msk, int fb_mib)
+{
+	struct net *net = sock_net((struct sock *)msk);
+
+	if (__mptcp_check_fallback(msk))
+		return true;
+
+	spin_lock_bh(&msk->fallback_lock);
+	if (!msk->allow_infinite_fallback) {
+		spin_unlock_bh(&msk->fallback_lock);
+		return false;
+	}
+
+	msk->allow_subflows = false;
+	set_bit(MPTCP_FALLBACK_DONE, &msk->flags);
+	__MPTCP_INC_STATS(net, fb_mib);
+	spin_unlock_bh(&msk->fallback_lock);
+	return true;
+}
+
 static int __mptcp_socket_create(struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow;
@@ -561,10 +581,7 @@ static bool mptcp_check_data_fin(struct sock *sk)
 
 static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk)
 {
-	if (mptcp_try_fallback(ssk)) {
-		MPTCP_INC_STATS(sock_net(ssk),
-				MPTCP_MIB_DSSCORRUPTIONFALLBACK);
-	} else {
+	if (!mptcp_try_fallback(ssk, MPTCP_MIB_DSSCORRUPTIONFALLBACK)) {
 		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET);
 		mptcp_subflow_reset(ssk);
 	}
@@ -1143,12 +1160,12 @@ static void mptcp_update_infinite_map(struct mptcp_sock *msk,
 	mpext->infinite_map = 1;
 	mpext->data_len = 0;
 
-	if (!mptcp_try_fallback(ssk)) {
+	if (!mptcp_try_fallback(ssk, MPTCP_MIB_INFINITEMAPTX)) {
+		MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED);
 		mptcp_subflow_reset(ssk);
 		return;
 	}
 
-	MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPTX);
 	mptcp_subflow_ctx(ssk)->send_infinite_map = 0;
 	pr_fallback(msk);
 }
@@ -3689,16 +3706,15 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	 * TCP option space.
 	 */
 	if (rcu_access_pointer(tcp_sk(ssk)->md5sig_info))
-		mptcp_subflow_early_fallback(msk, subflow);
+		mptcp_early_fallback(msk, subflow, MPTCP_MIB_MD5SIGFALLBACK);
 #endif
 	if (subflow->request_mptcp) {
-		if (mptcp_active_should_disable(sk)) {
-			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDISABLED);
-			mptcp_subflow_early_fallback(msk, subflow);
-		} else if (mptcp_token_new_connect(ssk) < 0) {
-			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_TOKENFALLBACKINIT);
-			mptcp_subflow_early_fallback(msk, subflow);
-		}
+		if (mptcp_active_should_disable(sk))
+			mptcp_early_fallback(msk, subflow,
+					     MPTCP_MIB_MPCAPABLEACTIVEDISABLED);
+		else if (mptcp_token_new_connect(ssk) < 0)
+			mptcp_early_fallback(msk, subflow,
+					     MPTCP_MIB_TOKENFALLBACKINIT);
 	}
 
 	WRITE_ONCE(msk->write_seq, subflow->idsn);