sctp: return true only for pathmtu update in sctp_transport_pl_toobig

sctp_transport_pl_toobig() supposes to return true only if there's
pathmtu update, so that in sctp_icmp_frag_needed() it would call
sctp_assoc_sync_pmtu() and sctp_retransmit(). This patch is to fix
these return places in sctp_transport_pl_toobig().

Fixes: 8369640 ("sctp: do state transition when receiving an icmp TOOBIG packet")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/transport.c

@@ -368,6 +368,7 @@ static bool sctp_transport_pl_toobig(struct sctp_transport *t, u32 pmtu)
 
 			t->pl.pmtu = SCTP_BASE_PLPMTU;
 			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			return true;
 		}
 	} else if (t->pl.state == SCTP_PL_SEARCH) {
 		if (pmtu >= SCTP_BASE_PLPMTU && pmtu < t->pl.pmtu) {
@@ -378,11 +379,10 @@ static bool sctp_transport_pl_toobig(struct sctp_transport *t, u32 pmtu)
 			t->pl.probe_high = 0;
 			t->pl.pmtu = SCTP_BASE_PLPMTU;
 			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			return true;
 		} else if (pmtu > t->pl.pmtu && pmtu < t->pl.probe_size) {
 			t->pl.probe_size = pmtu;
 			t->pl.probe_count = 0;
-
-			return false;
 		}
 	} else if (t->pl.state == SCTP_PL_COMPLETE) {
 		if (pmtu >= SCTP_BASE_PLPMTU && pmtu < t->pl.pmtu) {
@@ -393,10 +393,11 @@ static bool sctp_transport_pl_toobig(struct sctp_transport *t, u32 pmtu)
 			t->pl.probe_high = 0;
 			t->pl.pmtu = SCTP_BASE_PLPMTU;
 			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
+			return true;
 		}
 	}
 
-	return true;
+	return false;
 }
 
 bool sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)