mptcp: wake-up readers only for in sequence data
Currently we rely on the subflow->data_avail field, which is subject to
races:
ssk1
skb len = 500 DSS(seq=1, len=1000, off=0)
# data_avail == MPTCP_SUBFLOW_DATA_AVAIL
ssk2
skb len = 500 DSS(seq = 501, len=1000)
# data_avail == MPTCP_SUBFLOW_DATA_AVAIL
ssk1
skb len = 500 DSS(seq = 1, len=1000, off =500)
# still data_avail == MPTCP_SUBFLOW_DATA_AVAIL,
# as the skb is covered by a pre-existing map,
# which was in-sequence at reception time.
Instead we can explicitly check if some has been received in-sequence,
propagating the info from __mptcp_move_skbs_from_subflow().
Additionally add the 'ONCE' annotation to the 'data_avail' memory
access, as msk will read it outside the subflow socket lock.
Fixes: 648ef4b88673 ("mptcp: Implement MPTCP receive path")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
3 files changed
