Commit 8c728940 authored Jul 15, 2020 by Davide Caratti Committed by David S. Miller Jul 17, 2020

mptcp: silence warning in subflow_data_ready()



since commit d47a7215 ("mptcp: fix race in subflow_data_ready()"), it
is possible to observe a regression in MP_JOIN kselftests. For sockets in
TCP_CLOSE state, it's not sufficient to just wake up the main socket: we
also need to ensure that received data are made available to the reader.
Silence the WARN_ON_ONCE() in these cases: it preserves the syzkaller fix
and restores kselftests	when they are ran as follows:

  # while true; do
  > make KBUILD_OUTPUT=/tmp/kselftest TARGETS=net/mptcp kselftest
  > done

Reported-by: Florian Westphal <fw@strlen.de>
Fixes: d47a7215 ("mptcp: fix race in subflow_data_ready()")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/47


Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 79814d81

net/mptcp/subflow.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -869,18 +869,19 @@ void mptcp_space(const struct sock ssk, int space, int *full_space)
		static void subflow_data_ready(struct sock *sk)
		{
		struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
		u16 state = 1 << inet_sk_state_load(sk);
		struct sock *parent = subflow->conn;
		struct mptcp_sock *msk;

		msk = mptcp_sk(parent);
		if ((1 << inet_sk_state_load(sk)) & (TCPF_LISTEN \| TCPF_CLOSE)) {
		if (state & TCPF_LISTEN) {
		set_bit(MPTCP_DATA_READY, &msk->flags);
		parent->sk_data_ready(parent);
		return;
		}

		WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
		!subflow->mp_join);
		!subflow->mp_join && !(state & TCPF_CLOSE));

		if (mptcp_subflow_data_available(sk))
		mptcp_data_ready(parent, sk);

Admin message