From 1dc68c194571acc4027de5f8378227d0c0ff7e13 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 22 Jun 2021 14:04:53 -0400 Subject: sctp: do state transition when PROBE_COUNT == MAX_PROBES on HB send path The state transition is described in rfc8899#section-5.2, PROBE_COUNT == MAX_PROBES means the probe fails for MAX times, and the state transition includes: - Base -> Error, occurs when BASE_PLPMTU Confirmation Fails, pl.pmtu is set to SCTP_MIN_PLPMTU, probe_size is still SCTP_BASE_PLPMTU; - Search -> Base, occurs when Black Hole Detected, pl.pmtu is set to SCTP_BASE_PLPMTU, probe_size is set back to SCTP_BASE_PLPMTU; - Search Complete -> Base, occurs when Black Hole Detected pl.pmtu is set to SCTP_BASE_PLPMTU, probe_size is set back to SCTP_BASE_PLPMTU; Note a black hole is encountered when a sender is unaware that packets are not being delivered to the destination endpoint. So it includes the probe failures with equal probe_size to pl.pmtu, and definitely not include that with greater probe_size than pl.pmtu. The later one is the normal probe failure where probe_size should decrease back to pl.pmtu and pl.probe_high is set. pl.probe_high would be used on HB ACK recv path in the next patch. Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/transport.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'net/sctp/transport.c') diff --git a/net/sctp/transport.c b/net/sctp/transport.c index ca3343c2c80e..99620d86e317 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -261,6 +261,50 @@ void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk) transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; } +void sctp_transport_pl_send(struct sctp_transport *t) +{ + pr_debug("%s: PLPMTUD: transport: %p, state: %d, pmtu: %d, size: %d, high: %d\n", + __func__, t, t->pl.state, t->pl.pmtu, t->pl.probe_size, t->pl.probe_high); + + if (t->pl.probe_count < SCTP_MAX_PROBES) { + t->pl.probe_count++; + return; + } + + if (t->pl.state == SCTP_PL_BASE) { + if (t->pl.probe_size == SCTP_BASE_PLPMTU) { /* BASE_PLPMTU Confirmation Failed */ + t->pl.state = SCTP_PL_ERROR; /* Base -> Error */ + + t->pl.pmtu = SCTP_MIN_PLPMTU; + t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t); + sctp_assoc_sync_pmtu(t->asoc); + } + } else if (t->pl.state == SCTP_PL_SEARCH) { + if (t->pl.pmtu == t->pl.probe_size) { /* Black Hole Detected */ + t->pl.state = SCTP_PL_BASE; /* Search -> Base */ + t->pl.probe_size = SCTP_BASE_PLPMTU; + t->pl.probe_high = 0; + + t->pl.pmtu = SCTP_BASE_PLPMTU; + t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t); + sctp_assoc_sync_pmtu(t->asoc); + } else { /* Normal probe failure. */ + t->pl.probe_high = t->pl.probe_size; + t->pl.probe_size = t->pl.pmtu; + } + } else if (t->pl.state == SCTP_PL_COMPLETE) { + if (t->pl.pmtu == t->pl.probe_size) { /* Black Hole Detected */ + t->pl.state = SCTP_PL_BASE; /* Search Complete -> Base */ + t->pl.probe_size = SCTP_BASE_PLPMTU; + + t->pl.pmtu = SCTP_BASE_PLPMTU; + t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t); + sctp_assoc_sync_pmtu(t->asoc); + } + } + t->pl.probe_count = 1; +} + bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu) { struct dst_entry *dst = sctp_transport_dst_check(t); -- cgit