Re: [PATCH net-next 03/10] mptcp: add SIOCINQ, OUTQ and OUTQNSD ioctls

Hello,

On Mon, 2021-12-06 at 17:16 -0800, Jakub Kicinski wrote:

On Fri,  3 Dec 2021 14:35:34 -0800 Mat Martineau wrote:

quoted

+		if (sk->sk_state == TCP_LISTEN)
+			return -EINVAL;
+
+		lock_sock(sk);
+		__mptcp_move_skbs(msk);
+		answ = mptcp_inq_hint(sk);
+		release_sock(sk);

The raciness is not harmful here?

Thank you for the careful review!

AFAICS the race between the socket state test and the receive queue
lenght estimate is not harmful: if a socket is concurrently
disconnected and moved to a listen status, mptcp_inq_hint() will return
0, as plain TCP would do in the same scenario - all the fields accessed
by __mptcp_move_skbs() and mptcp_inq_hint() will be in a consistant
status (modulo unknown bugs).

Cheers,

Paolo