Merge branch 'sctp-plpmtud-fixes'

Xin Long says:

====================
sctp: a couple of fixes for PLPMTUD

Four fixes included in this patchset:

  - fix the packet sending in Error state.
  - fix the timer stop when transport update dst.
  - fix the outer header len calculation.
  - fix the return value for toobig processing.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -626,7 +626,8 @@ static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize)
 
 static inline int sctp_transport_pl_hlen(struct sctp_transport *t)
 {
-	return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0);
+	return __sctp_mtu_payload(sctp_sk(t->asoc->base.sk), t, 0, 0) -
+	       sizeof(struct sctphdr);
 }
 
 static inline void sctp_transport_pl_reset(struct sctp_transport *t)
@@ -653,12 +654,10 @@ 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;
+	sctp_transport_reset_probe_timer(t);
 }
 
 static inline bool sctp_transport_pl_enabled(struct sctp_transport *t)

net/sctp/output.c

@@ -581,13 +581,16 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
 	sk = chunk->skb->sk;
 
-	/* check gso */
 	if (packet->size > tp->pathmtu && !packet->ipfragok && !chunk->pmtu_probe) {
-		if (!sk_can_gso(sk)) {
-			pr_err_once("Trying to GSO but underlying device doesn't support it.");
-			goto out;
+		if (tp->pl.state == SCTP_PL_ERROR) { /* do IP fragmentation if in Error state */
+			packet->ipfragok = 1;
+		} else {
+			if (!sk_can_gso(sk)) { /* check gso */
+				pr_err_once("Trying to GSO but underlying device doesn't support it.");
+				goto out;
+			}
+			gso = 1;
 		}
-		gso = 1;
 	}
 
 	/* alloc head skb */

net/sctp/transport.c

@@ -269,7 +269,7 @@ bool sctp_transport_pl_send(struct sctp_transport *t)
 		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->pl.pmtu = SCTP_BASE_PLPMTU;
 			t->pathmtu = t->pl.pmtu + sctp_transport_pl_hlen(t);
 			sctp_assoc_sync_pmtu(t->asoc);
 		}
@@ -366,8 +366,9 @@ static bool sctp_transport_pl_toobig(struct sctp_transport *t, u32 pmtu)
 		if (pmtu >= SCTP_MIN_PLPMTU && pmtu < SCTP_BASE_PLPMTU) {
 			t->pl.state = SCTP_PL_ERROR; /* Base -> Error */
 
-			t->pl.pmtu = SCTP_MIN_PLPMTU;
+			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)