rxrpc: Provide more refcount helper functions

Provide refcount helper functions for connections so that the code doesn't
touch local or connection usage counts directly.

Also make it such that local and peer put functions can take a NULL
pointer.
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/af_rxrpc.c

@@ -674,11 +674,8 @@ static int rxrpc_release_sock(struct sock *sk)
 	flush_workqueue(rxrpc_workqueue);
 	rxrpc_purge_queue(&sk->sk_receive_queue);
 
-	if (rx->local) {
-		rxrpc_put_local(rx->local);
-		rx->local = NULL;
-	}
-
+	rxrpc_put_local(rx->local);
+	rx->local = NULL;
 	key_put(rx->key);
 	rx->key = NULL;
 	key_put(rx->securities);

net/rxrpc/ar-internal.h

@@ -597,6 +597,17 @@ static inline bool rxrpc_conn_is_service(const struct rxrpc_connection *conn)
 	return conn->proto.in_clientflag;
 }
 
+static inline void rxrpc_get_connection(struct rxrpc_connection *conn)
+{
+	atomic_inc(&conn->usage);
+}
+
+static inline
+struct rxrpc_connection *rxrpc_get_connection_maybe(struct rxrpc_connection *conn)
+{
+	return atomic_inc_not_zero(&conn->usage) ? conn : NULL;
+}
+
 /*
  * input.c
  */
@@ -645,7 +656,7 @@ struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local)
 
 static inline void rxrpc_put_local(struct rxrpc_local *local)
 {
-	if (atomic_dec_and_test(&local->usage))
+	if (local && atomic_dec_and_test(&local->usage))
 		__rxrpc_put_local(local);
 }
 
@@ -702,7 +713,7 @@ struct rxrpc_peer *rxrpc_get_peer_maybe(struct rxrpc_peer *peer)
 extern void __rxrpc_put_peer(struct rxrpc_peer *peer);
 static inline void rxrpc_put_peer(struct rxrpc_peer *peer)
 {
-	if (atomic_dec_and_test(&peer->usage))
+	if (peer && atomic_dec_and_test(&peer->usage))
 		__rxrpc_put_peer(peer);
 }
 

net/rxrpc/call_accept.c

@@ -141,7 +141,7 @@ static int rxrpc_accept_incoming_call(struct rxrpc_local *local,
 			_debug("await conn sec");
 			list_add_tail(&call->accept_link, &rx->secureq);
 			call->conn->state = RXRPC_CONN_SERVER_CHALLENGING;
-			atomic_inc(&call->conn->usage);
+			rxrpc_get_connection(call->conn);
 			set_bit(RXRPC_CONN_CHALLENGE, &call->conn->events);
 			rxrpc_queue_conn(call->conn);
 		} else {

net/rxrpc/call_object.c

@@ -515,7 +515,7 @@ struct rxrpc_call *rxrpc_incoming_call(struct rxrpc_sock *rx,
 	rb_insert_color(&call->conn_node, &conn->calls);
 	conn->channels[call->channel] = call;
 	sock_hold(&rx->sk);
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	write_unlock_bh(&conn->lock);
 
 	spin_lock(&conn->params.peer->lock);

net/rxrpc/conn_event.c

@@ -263,7 +263,7 @@ void rxrpc_process_connection(struct work_struct *work)
 
 	_enter("{%d}", conn->debug_id);
 
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 
 	if (test_and_clear_bit(RXRPC_CONN_CHALLENGE, &conn->events)) {
 		rxrpc_secure_connection(conn);

net/rxrpc/conn_object.c

@@ -333,7 +333,7 @@ static int rxrpc_connect_exclusive(struct rxrpc_sock *rx,
 	 * channel.
 	 */
 	chan = 0;
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	conn->avail_calls = RXRPC_MAXCALLS - 1;
 	conn->channels[chan] = call;
 	conn->call_counter = 1;
@@ -392,7 +392,7 @@ int rxrpc_connect_call(struct rxrpc_sock *rx,
 			       conn->channels[1] == NULL ||
 			       conn->channels[2] == NULL ||
 			       conn->channels[3] == NULL);
-			atomic_inc(&conn->usage);
+			rxrpc_get_connection(conn);
 			break;
 		}
 
@@ -412,7 +412,7 @@ int rxrpc_connect_call(struct rxrpc_sock *rx,
 			       conn->channels[1] == NULL &&
 			       conn->channels[2] == NULL &&
 			       conn->channels[3] == NULL);
-			atomic_inc(&conn->usage);
+			rxrpc_get_connection(conn);
 			list_move(&conn->bundle_link, &bundle->avail_conns);
 			break;
 		}
@@ -629,7 +629,7 @@ rxrpc_incoming_connection(struct rxrpc_transport *trans, struct sk_buff *skb)
 		read_unlock_bh(&trans->conn_lock);
 		goto security_mismatch;
 	}
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	read_unlock_bh(&trans->conn_lock);
 	goto success;
 
@@ -639,7 +639,7 @@ rxrpc_incoming_connection(struct rxrpc_transport *trans, struct sk_buff *skb)
 		write_unlock_bh(&trans->conn_lock);
 		goto security_mismatch;
 	}
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	write_unlock_bh(&trans->conn_lock);
 	kfree(candidate);
 	goto success;
@@ -698,7 +698,7 @@ struct rxrpc_connection *rxrpc_find_connection(struct rxrpc_transport *trans,
 	return NULL;
 
 found:
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	read_unlock_bh(&trans->conn_lock);
 	_leave(" = %p", conn);
 	return conn;

net/rxrpc/input.c

@@ -580,7 +580,7 @@ static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
 {
 	_enter("%p,%p", conn, skb);
 
-	atomic_inc(&conn->usage);
+	rxrpc_get_connection(conn);
 	skb_queue_tail(&conn->rx_queue, skb);
 	rxrpc_queue_conn(conn);
 }

net/rxrpc/local_object.c

@@ -209,7 +209,7 @@ struct rxrpc_local *rxrpc_lookup_local(const struct sockaddr_rxrpc *srx)
 		 * bind the transport socket may still fail if we're attempting
 		 * to use a local address that the dying object is still using.
 		 */
-		if (!atomic_inc_not_zero(&local->usage)) {
+		if (!rxrpc_get_local_maybe(local)) {
 			cursor = cursor->next;
 			list_del_init(&local->link);
 			break;