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mptcp: silence warning in subflow_data_ready()

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since commit d47a721520 ("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: d47a721520 ("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>
This commit is contained in:
Davide Caratti 2020-07-15 22:27:05 +02:00 committed by David S. Miller
parent 79814d8179
commit 8c72894048
1 changed files with 3 additions and 2 deletions
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5
net/mptcp/subflow.c
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@ -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);