sctp: introduce sctp_assoc_set_pmtu

All changes to asoc PMTU should now go through this wrapper, making it
easier to track them and to do other actions upon it.
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/structs.h

@@ -2097,6 +2097,7 @@ int sctp_assoc_update(struct sctp_association *old,
 
 __u32 sctp_association_get_next_tsn(struct sctp_association *);
 
+void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu);
 void sctp_assoc_sync_pmtu(struct sctp_association *asoc);
 void sctp_assoc_rwnd_increase(struct sctp_association *, unsigned int);
 void sctp_assoc_rwnd_decrease(struct sctp_association *, unsigned int);

net/sctp/associola.c

@@ -660,13 +660,9 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
 	 * If not and the current association PMTU is higher than the new
 	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
 	 */
-	if (asoc->pathmtu)
-		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
-	else
-		asoc->pathmtu = peer->pathmtu;
-
-	pr_debug("%s: association:%p PMTU set to %d\n", __func__, asoc,
-		 asoc->pathmtu);
+	sctp_assoc_set_pmtu(asoc, asoc->pathmtu ?
+				  min_t(int, peer->pathmtu, asoc->pathmtu) :
+				  peer->pathmtu);
 
 	peer->pmtu_pending = 0;
 
@@ -1374,6 +1370,15 @@ sctp_assoc_choose_alter_transport(struct sctp_association *asoc,
 	}
 }
 
+void sctp_assoc_set_pmtu(struct sctp_association *asoc, __u32 pmtu)
+{
+	if (asoc->pathmtu != pmtu)
+		asoc->pathmtu = pmtu;
+
+	pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,
+		 asoc->pathmtu, asoc->frag_point);
+}
+
 /* Update the association's pmtu and frag_point by going through all the
  * transports. This routine is called when a transport's PMTU has changed.
  */
@@ -1397,7 +1402,7 @@ void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
 			pmtu = t->pathmtu;
 	}
 
-	asoc->pathmtu = pmtu;
+	sctp_assoc_set_pmtu(asoc, pmtu);
 	asoc->frag_point = sctp_frag_point(asoc, pmtu);
 
 	pr_debug("%s: asoc:%p, pmtu:%d, frag_point:%d\n", __func__, asoc,

net/sctp/socket.c

@@ -2539,7 +2539,7 @@ static int sctp_apply_peer_addr_params(struct sctp_paddrparams *params,
 			trans->pathmtu = params->spp_pathmtu;
 			sctp_assoc_sync_pmtu(asoc);
 		} else if (asoc) {
-			asoc->pathmtu = params->spp_pathmtu;
+			sctp_assoc_set_pmtu(asoc, params->spp_pathmtu);
 		} else {
 			sp->pathmtu = params->spp_pathmtu;
 		}