[SCTP]: Remove temporary associations from backlog and hash.

Every time SCTP creates a temporary association, the stack hashes it,
puts it on a list of endpoint associations and increments the backlog.
However, the lifetime of a temporary association is the processing time
of a current packet and it's destroyed after that. In fact, we don't
really want anyone else finding this association. There is no reason to
do this extra work.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/associola.c

@@ -346,11 +346,18 @@ void sctp_association_free(struct sctp_association *asoc)
 	struct list_head *pos, *temp;
 	int i;
 
-	list_del(&asoc->asocs);
+	/* Only real associations count against the endpoint, so
+	 * don't bother for if this is a temporary association.
+	 */
+	if (!asoc->temp) {
+		list_del(&asoc->asocs);
 
-	/* Decrement the backlog value for a TCP-style listening socket. */
-	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
-		sk->sk_ack_backlog--;
+		/* Decrement the backlog value for a TCP-style listening
+		 * socket.
+		 */
+		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
+			sk->sk_ack_backlog--;
+	}
 
 	/* Mark as dead, so other users can know this structure is
 	 * going away.

net/sctp/endpointola.c

@@ -144,6 +144,13 @@ void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
 {
 	struct sock *sk = ep->base.sk;
 
+	/* If this is a temporary association, don't bother
+	 * since we'll be removing it shortly and don't
+	 * want anyone to find it anyway.
+	 */
+	if (asoc->temp)
+		return;
+
 	/* Now just add it to our list of asocs */
 	list_add_tail(&asoc->asocs, &ep->asocs);
 

net/sctp/input.c

@@ -771,6 +771,9 @@ static void __sctp_hash_established(struct sctp_association *asoc)
 /* Add an association to the hash. Local BH-safe. */
 void sctp_hash_established(struct sctp_association *asoc)
 {
+	if (asoc->temp)
+		return;
+
 	sctp_local_bh_disable();
 	__sctp_hash_established(asoc);
 	sctp_local_bh_enable();
@@ -804,6 +807,9 @@ static void __sctp_unhash_established(struct sctp_association *asoc)
 /* Remove association from the hash table.  Local BH-safe. */
 void sctp_unhash_established(struct sctp_association *asoc)
 {
+	if (asoc->temp)
+		return;
+
 	sctp_local_bh_disable();
 	__sctp_unhash_established(asoc);
 	sctp_local_bh_enable();