Merge branch 'mptcp-more-fixes-for-6-1'

Matthieu Baerts says:

====================
mptcp: More fixes for 6.1

Patch 1 makes sure data received after a close will still be processed
and acked as exepected. This is a regression for a commit introduced
in v5.11.

Patch 2 fixes a kernel deadlock found when working on validating TFO
with a listener MPTCP socket. This is not directly linked to TFO but
it is easier to reproduce the issue with it. This fixes a bug introduced
by a commit from v6.0.
====================

Link: https://lore.kernel.org/r/20221128154239.1999234-1-matthieu.baerts@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/protocol.c

@@ -2354,12 +2354,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		goto out;
 	}
 
-	/* if we are invoked by the msk cleanup code, the subflow is
-	 * already orphaned
-	 */
-	if (ssk->sk_socket)
-		sock_orphan(ssk);
-
+	sock_orphan(ssk);
 	subflow->disposable = 1;
 
 	/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
@@ -2940,7 +2935,11 @@ bool __mptcp_close(struct sock *sk, long timeout)
 		if (ssk == msk->first)
 			subflow->fail_tout = 0;
 
-		sock_orphan(ssk);
+		/* detach from the parent socket, but allow data_ready to
+		 * push incoming data into the mptcp stack, to properly ack it
+		 */
+		ssk->sk_socket = NULL;
+		ssk->sk_wq = NULL;
 		unlock_sock_fast(ssk, slow);
 	}
 	sock_orphan(sk);

net/mptcp/subflow.c

@@ -1745,16 +1745,16 @@ void mptcp_subflow_queue_clean(struct sock *listener_ssk)
 
 	for (msk = head; msk; msk = next) {
 		struct sock *sk = (struct sock *)msk;
-		bool slow, do_cancel_work;
+		bool do_cancel_work;
 
 		sock_hold(sk);
-		slow = lock_sock_fast_nested(sk);
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 		next = msk->dl_next;
 		msk->first = NULL;
 		msk->dl_next = NULL;
 
 		do_cancel_work = __mptcp_close(sk, 0);
-		unlock_sock_fast(sk, slow);
+		release_sock(sk);
 		if (do_cancel_work)
 			mptcp_cancel_work(sk);
 		sock_put(sk);