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| author | Paolo Abeni <pabeni@redhat.com> | 2021-06-11 00:59:41 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-06-11 01:47:44 +0200 |
| commit | 99d1055ce2469dca3dd14be0991ff8133e25e3d0 (patch) | |
| tree | 6e9c1abe8206b353d21f387100e429a36d785c52 /net/mptcp/subflow.c | |
| parent | mptcp: try harder to borrow memory from subflow under pressure (diff) | |
| download | linux-99d1055ce2469dca3dd14be0991ff8133e25e3d0.tar.xz linux-99d1055ce2469dca3dd14be0991ff8133e25e3d0.zip | |
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>
Diffstat (limited to 'net/mptcp/subflow.c')
| -rw-r--r-- | net/mptcp/subflow.c | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index ef3d037f984a..ebb898acd65a 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1000,7 +1000,7 @@ static bool subflow_check_data_avail(struct sock *ssk) struct sk_buff *skb; if (!skb_peek(&ssk->sk_receive_queue)) - subflow->data_avail = 0; + WRITE_ONCE(subflow->data_avail, 0); if (subflow->data_avail) return true; @@ -1039,18 +1039,13 @@ static bool subflow_check_data_avail(struct sock *ssk) ack_seq = mptcp_subflow_get_mapped_dsn(subflow); pr_debug("msk ack_seq=%llx subflow ack_seq=%llx", old_ack, ack_seq); - if (ack_seq == old_ack) { - subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL; - break; - } else if (after64(ack_seq, old_ack)) { - subflow->data_avail = MPTCP_SUBFLOW_OOO_DATA; - break; + if (unlikely(before64(ack_seq, old_ack))) { + mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); + continue; } - /* only accept in-sequence mapping. Old values are spurious - * retransmission - */ - mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq); + WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); + break; } return true; @@ -1070,7 +1065,7 @@ fallback: subflow->reset_transient = 0; subflow->reset_reason = MPTCP_RST_EMPTCP; tcp_send_active_reset(ssk, GFP_ATOMIC); - subflow->data_avail = 0; + WRITE_ONCE(subflow->data_avail, 0); return false; } @@ -1080,7 +1075,7 @@ fallback: subflow->map_seq = READ_ONCE(msk->ack_seq); subflow->map_data_len = skb->len; subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset; - subflow->data_avail = MPTCP_SUBFLOW_DATA_AVAIL; + WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); return true; } @@ -1092,7 +1087,7 @@ bool mptcp_subflow_data_available(struct sock *sk) if (subflow->map_valid && mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) { subflow->map_valid = 0; - subflow->data_avail = 0; + WRITE_ONCE(subflow->data_avail, 0); pr_debug("Done with mapping: seq=%u data_len=%u", subflow->map_subflow_seq, |