sctp: add the probe timer in transport for PLPMTUD

There are 3 timers described in rfc8899#section-5.1.1:

  PROBE_TIMER, PMTU_RAISE_TIMER, CONFIRMATION_TIMER

This patches adds a 'probe_timer' in transport, and it works as either
PROBE_TIMER or PMTU_RAISE_TIMER. At most time, it works as PROBE_TIMER
and expires every a 'probe_interval' time to send the HB probe packet.
When transport pl enters COMPLETE state, it works as PMTU_RAISE_TIMER
and expires in 'probe_interval * 30' time to go back to SEARCH state
and do searching again.

SCTP HB is an acknowledged packet, CONFIRMATION_TIMER is not needed.

The timer will start when transport pl enters BASE state and stop
when it enters DISABLED state.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 08347d3f004f..f7e083602c10 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -635,10 +635,14 @@ static inline void sctp_transport_pl_reset(struct sctp_transport *t)
 			t->pl.state = SCTP_PL_BASE;
 			t->pl.pmtu = SCTP_BASE_PLPMTU;
 			t->pl.probe_size = SCTP_BASE_PLPMTU;
+			sctp_transport_reset_probe_timer(t);
 		}
 	} else {
-		if (t->pl.state != SCTP_PL_DISABLED)
+		if (t->pl.state != SCTP_PL_DISABLED) {
+			if (del_timer(&t->probe_timer))
+				sctp_transport_put(t);
 			t->pl.state = SCTP_PL_DISABLED;
+		}
 	}
 }
 
@@ -647,6 +651,9 @@ static inline void sctp_transport_pl_update(struct sctp_transport *t)
 	if (t->pl.state == SCTP_PL_DISABLED)
 		return;
 
+	if (del_timer(&t->probe_timer))
+		sctp_transport_put(t);
+
 	t->pl.state = SCTP_PL_BASE;
 	t->pl.pmtu = SCTP_BASE_PLPMTU;
 	t->pl.probe_size = SCTP_BASE_PLPMTU;