sctp: apply rhashtable api to send/recv path

apply lookup apis to two functions, for __sctp_endpoint_lookup_assoc
and __sctp_lookup_association, it's invoked in the protection of sock
lock, it will be safe, but sctp_lookup_association need to call
rcu_read_lock() and to detect the t->dead to protect it.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c
index 9da76ba..8838bf4 100644
--- a/net/sctp/endpointola.c
+++ b/net/sctp/endpointola.c
@@ -314,8 +314,8 @@
 }
 
 /* Find the association that goes with this chunk.
- * We do a linear search of the associations for this endpoint.
- * We return the matching transport address too.
+ * We lookup the transport from hashtable at first, then get association
+ * through t->assoc.
  */
 static struct sctp_association *__sctp_endpoint_lookup_assoc(
 	const struct sctp_endpoint *ep,
@@ -323,12 +323,7 @@
 	struct sctp_transport **transport)
 {
 	struct sctp_association *asoc = NULL;
-	struct sctp_association *tmp;
-	struct sctp_transport *t = NULL;
-	struct sctp_hashbucket *head;
-	struct sctp_ep_common *epb;
-	int hash;
-	int rport;
+	struct sctp_transport *t;
 
 	*transport = NULL;
 
@@ -337,26 +332,12 @@
 	 */
 	if (!ep->base.bind_addr.port)
 		goto out;
+	t = sctp_epaddr_lookup_transport(ep, paddr);
+	if (!t || t->asoc->temp)
+		goto out;
 
-	rport = ntohs(paddr->v4.sin_port);
-
-	hash = sctp_assoc_hashfn(sock_net(ep->base.sk), ep->base.bind_addr.port,
-				 rport);
-	head = &sctp_assoc_hashtable[hash];
-	read_lock(&head->lock);
-	sctp_for_each_hentry(epb, &head->chain) {
-		tmp = sctp_assoc(epb);
-		if (tmp->ep != ep || rport != tmp->peer.port)
-			continue;
-
-		t = sctp_assoc_lookup_paddr(tmp, paddr);
-		if (t) {
-			asoc = tmp;
-			*transport = t;
-			break;
-		}
-	}
-	read_unlock(&head->lock);
+	*transport = t;
+	asoc = t->asoc;
 out:
 	return asoc;
 }