diff options
| author | Aananth V <aananthv@google.com> | 2023-09-14 14:36:20 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-09-16 13:42:34 +0100 |
| commit | e326578a21414738de45f77badd332fb00bd0f58 (patch) | |
| tree | 0432d38ae1907442f930e6a3b84d257f43e3d23e /net/ipv4/tcp_input.c | |
| parent | 50675d84e3995f2606306b5e23e6847273a730e9 (diff) | |
tcp: call tcp_try_undo_recovery when an RTOd TFO SYNACK is ACKed
For passive TCP Fast Open sockets that had SYN/ACK timeout and did not
send more data in SYN_RECV, upon receiving the final ACK in 3WHS, the
congestion state may awkwardly stay in CA_Loss mode unless the CA state
was undone due to TCP timestamp checks. However, if
tcp_rcv_synrecv_state_fastopen() decides not to undo, then we should
enter CA_Open, because at that point we have received an ACK covering
the retransmitted SYNACKs. Currently, the icsk_ca_state is only set to
CA_Open after we receive an ACK for a data-packet. This is because
tcp_ack does not call tcp_fastretrans_alert (and tcp_process_loss) if
!prior_packets
Note that tcp_process_loss() calls tcp_try_undo_recovery(), so having
tcp_rcv_synrecv_state_fastopen() decide that if we're in CA_Loss we
should call tcp_try_undo_recovery() is consistent with that, and
low risk.
Fixes: dad8cea7add9 ("tcp: fix TFO SYNACK undo to avoid double-timestamp-undo")
Signed-off-by: Aananth V <aananthv@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 41b471748437..8d2c91703158 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6444,22 +6444,23 @@ reset_and_undo: static void tcp_rcv_synrecv_state_fastopen(struct sock *sk) { + struct tcp_sock *tp = tcp_sk(sk); struct request_sock *req; /* If we are still handling the SYNACK RTO, see if timestamp ECR allows * undo. If peer SACKs triggered fast recovery, we can't undo here. */ - if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) - tcp_try_undo_loss(sk, false); + if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss && !tp->packets_out) + tcp_try_undo_recovery(sk); /* Reset rtx states to prevent spurious retransmits_timed_out() */ - tcp_sk(sk)->retrans_stamp = 0; + tp->retrans_stamp = 0; inet_csk(sk)->icsk_retransmits = 0; /* Once we leave TCP_SYN_RECV or TCP_FIN_WAIT_1, * we no longer need req so release it. */ - req = rcu_dereference_protected(tcp_sk(sk)->fastopen_rsk, + req = rcu_dereference_protected(tp->fastopen_rsk, lockdep_sock_is_held(sk)); reqsk_fastopen_remove(sk, req, false); |