From: Paolo Abeni pabeni@redhat.com
commit 52557dbc7538ecceb27ef2206719a47a8039a335 upstream.
MPJ subflows are not exposed as fds to user spaces. As such, incoming MPJ subflows are removed from the accept queue by tcp_check_req()/tcp_get_cookie_sock().
Later tcp_child_process() invokes subflow_data_ready() on the parent socket regardless of the subflow kind, leading to poll wakeups even if the later accept will block.
Address the issue by double-checking the queue state before waking the user-space.
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/164 Reported-by: Dr. David Alan Gilbert dgilbert@redhat.com Fixes: f296234c98a8 ("mptcp: Add handling of incoming MP_JOIN requests") Reviewed-by: Mat Martineau mathew.j.martineau@linux.intel.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/subflow.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -981,6 +981,12 @@ static void subflow_data_ready(struct so
msk = mptcp_sk(parent); if (state & TCPF_LISTEN) { + /* MPJ subflow are removed from accept queue before reaching here, + * avoid stray wakeups + */ + if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue)) + return; + set_bit(MPTCP_DATA_READY, &msk->flags); parent->sk_data_ready(parent); return;