When doing plpmtu probe, the probe size is growing every time when it
receives the ACK during the Search state until the probe fails. When
the failure occurs, pl.probe_high is set and it goes to the Complete
state.
However, if the link pmtu is huge, like 65535 in loopback_dev, the probe
eventually keeps using SCTP_MAX_PLPMTU as the probe size and never fails.
Because of that, pl.probe_high can not be set, and the plpmtu probe can
never go to the Complete state.
Fix it by setting pl.probe_high to SCTP_MAX_PLPMTU when the probe size
grows to SCTP_MAX_PLPMTU in sctp_transport_pl_recv(). Also, not allow
the probe size greater than SCTP_MAX_PLPMTU in the Complete state.
Fixes: b87641aff9e7 ("sctp: do state transition when a probe succeeds on HB ACK recv path")
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
v2:
- fix the probe size can't reach SCTP_MAX_PLPMTU, as Paolo suggested.
---
net/sctp/transport.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 2f66a2006517..2abe45af98e7 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -324,9 +324,12 @@ bool sctp_transport_pl_recv(struct sctp_transport *t)
t->pl.probe_size += SCTP_PL_BIG_STEP;
} else if (t->pl.state == SCTP_PL_SEARCH) {
if (!t->pl.probe_high) {
- t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP,
- SCTP_MAX_PLPMTU);
- return false;
+ if (t->pl.probe_size < SCTP_MAX_PLPMTU) {
+ t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP,
+ SCTP_MAX_PLPMTU);
+ return false;
+ }
+ t->pl.probe_high = SCTP_MAX_PLPMTU;
}
t->pl.probe_size += SCTP_PL_MIN_STEP;
if (t->pl.probe_size >= t->pl.probe_high) {
@@ -341,7 +344,7 @@ bool sctp_transport_pl_recv(struct sctp_transport *t)
} else if (t->pl.state == SCTP_PL_COMPLETE) {
/* Raise probe_size again after 30 * interval in Search Complete */
t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */
- t->pl.probe_size += SCTP_PL_MIN_STEP;
+ t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_MIN_STEP, SCTP_MAX_PLPMTU);
}
return t->pl.state == SCTP_PL_COMPLETE;
--
2.39.1
