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 <lucien.xin@xxxxxxxxx>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
---
include/net/sctp/structs.h | 1 +
net/sctp/sm_statefuns.c | 2 ++
net/sctp/transport.c | 44 ++++++++++++++++++++++++++++++++++++++
3 files changed, 47 insertions(+)
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index f7b056f5af37..31165720b28a 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1023,6 +1023,7 @@ bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu);
void sctp_transport_immediate_rtx(struct sctp_transport *);
void sctp_transport_dst_release(struct sctp_transport *t);
void sctp_transport_dst_confirm(struct sctp_transport *t);
+void sctp_transport_pl_send(struct sctp_transport *t);
/* This is the structure we use to queue packets as they come into
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 8edb9186112a..66c409e5b47c 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -1109,6 +1109,8 @@ enum sctp_disposition sctp_sf_send_probe(struct net *net,
if (!sctp_transport_pl_enabled(transport))
return SCTP_DISPOSITION_CONSUME;
+ sctp_transport_pl_send(transport);
+
reply = sctp_make_heartbeat(asoc, transport, transport->pl.probe_size);
if (!reply)
return SCTP_DISPOSITION_NOMEM;
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);
--
2.27.0
