From b08c8526cb1c0e92e0f831da434b769bc9c5198b Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Wed, 23 Feb 2022 21:57:12 +0100 Subject: [PATCH] mptcp: accurate SIOCOUTQ for fallback socket The MPTCP SIOCOUTQ implementation is not very accurate in case of fallback: it only measures the data in the MPTCP-level write queue, but it does not take in account the subflow write queue utilization. In case of fallback the first can be empty, while the latter is not. The above produces sporadic self-tests issues and can foul legit user-space application. Fix the issue additionally querying the subflow in case of fallback. Fixes: 644807e3e462 ("mptcp: add SIOCINQ, OUTQ and OUTQNSD ioctls") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/260 Reported-by: Matthieu Baerts Reviewed-by: Mat Martineau Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index f60f01b14fac4..12bb28c5007ed 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3294,6 +3294,17 @@ static int mptcp_ioctl_outq(const struct mptcp_sock *msk, u64 v) return 0; delta = msk->write_seq - v; + if (__mptcp_check_fallback(msk) && msk->first) { + struct tcp_sock *tp = tcp_sk(msk->first); + + /* the first subflow is disconnected after close - see + * __mptcp_close_ssk(). tcp_disconnect() moves the write_seq + * so ignore that status, too. + */ + if (!((1 << msk->first->sk_state) & + (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE))) + delta += READ_ONCE(tp->write_seq) - tp->snd_una; + } if (delta > INT_MAX) delta = INT_MAX;