1 files changed, 77 insertions, 3 deletions

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 80bbe96c0694..ba065b66551a 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -715,9 +715,12 @@ void mptcp_subflow_drop_ctx(struct sock *ssk)
 	if (!ctx)
 		return;
 
-	subflow_ulp_fallback(ssk, ctx);
-	if (ctx->conn)
-		sock_put(ctx->conn);
+	list_del(&mptcp_subflow_ctx(ssk)->node);
+	if (inet_csk(ssk)->icsk_ulp_ops) {
+		subflow_ulp_fallback(ssk, ctx);
+		if (ctx->conn)
+			sock_put(ctx->conn);
+	}
 
 	kfree_rcu(ctx, rcu);
 }
@@ -1802,6 +1805,77 @@ static void subflow_state_change(struct sock *sk)
 	}
 }
 
+void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
+{
+	struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
+	struct mptcp_sock *msk, *next, *head = NULL;
+	struct request_sock *req;
+	struct sock *sk;
+
+	/* build a list of all unaccepted mptcp sockets */
+	spin_lock_bh(&queue->rskq_lock);
+	for (req = queue->rskq_accept_head; req; req = req->dl_next) {
+		struct mptcp_subflow_context *subflow;
+		struct sock *ssk = req->sk;
+
+		if (!sk_is_mptcp(ssk))
+			continue;
+
+		subflow = mptcp_subflow_ctx(ssk);
+		if (!subflow || !subflow->conn)
+			continue;
+
+		/* skip if already in list */
+		sk = subflow->conn;
+		msk = mptcp_sk(sk);
+		if (msk->dl_next || msk == head)
+			continue;
+
+		sock_hold(sk);
+		msk->dl_next = head;
+		head = msk;
+	}
+	spin_unlock_bh(&queue->rskq_lock);
+	if (!head)
+		return;
+
+	/* can't acquire the msk socket lock under the subflow one,
+	 * or will cause ABBA deadlock
+	 */
+	release_sock(listener_ssk);
+
+	for (msk = head; msk; msk = next) {
+		sk = (struct sock *)msk;
+
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+		next = msk->dl_next;
+		msk->dl_next = NULL;
+
+		__mptcp_unaccepted_force_close(sk);
+		release_sock(sk);
+
+		/* lockdep will report a false positive ABBA deadlock
+		 * between cancel_work_sync and the listener socket.
+		 * The involved locks belong to different sockets WRT
+		 * the existing AB chain.
+		 * Using a per socket key is problematic as key
+		 * deregistration requires process context and must be
+		 * performed at socket disposal time, in atomic
+		 * context.
+		 * Just tell lockdep to consider the listener socket
+		 * released here.
+		 */
+		mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
+		mptcp_cancel_work(sk);
+		mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
+
+		sock_put(sk);
+	}
+
+	/* we are still under the listener msk socket lock */
+	lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
+}
+
 static int subflow_ulp_init(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);