[PATCH] RPC: separate TCP and UDP transport connection logic

 Create separate connection worker functions for managing UDP and TCP
 transport sockets.  This eliminates several dependencies on "xprt->stream".

 Test-plan:
 Destructive testing (unplugging the network temporarily).  Connectathon with
 v2, v3, and v4.

 Version: Thu, 11 Aug 2005 16:08:18 -0400
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/xprtsock.c

@@ -836,102 +836,118 @@ static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
 	return err;
 }
 
-static struct socket *xs_create(struct rpc_xprt *xprt, int proto, int resvport)
+/**
+ * xs_udp_connect_worker - set up a UDP socket
+ * @args: RPC transport to connect
+ *
+ * Invoked by a work queue tasklet.
+ */
+static void xs_udp_connect_worker(void *args)
 {
-	struct socket *sock;
-	int type, err;
-
-	dprintk("RPC:      xs_create(%s %d)\n",
-			   (proto == IPPROTO_UDP)? "udp" : "tcp", proto);
+	struct rpc_xprt *xprt = (struct rpc_xprt *) args;
+	struct socket *sock = xprt->sock;
+	int err, status = -EIO;
 
-	type = (proto == IPPROTO_UDP)? SOCK_DGRAM : SOCK_STREAM;
+	if (xprt->shutdown || xprt->addr.sin_port == 0)
+		goto out;
 
-	if ((err = sock_create_kern(PF_INET, type, proto, &sock)) < 0) {
-		dprintk("RPC:      can't create socket (%d).\n", -err);
-		return NULL;
-	}
+	dprintk("RPC:      xs_udp_connect_worker for xprt %p\n", xprt);
 
-	/* If the caller has the capability, bind to a reserved port */
-	if (resvport && xs_bindresvport(xprt, sock) < 0)
-		goto failed;
+	/* Start by resetting any existing state */
+	xs_close(xprt);
 
-	return sock;
+	if ((err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
+		dprintk("RPC:      can't create UDP transport socket (%d).\n", -err);
+		goto out;
+	}
 
-failed:
+	if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
 		sock_release(sock);
-	return NULL;
-}
+		goto out;
+	}
 
-static void xs_bind(struct rpc_xprt *xprt, struct socket *sock)
-{
+	if (!xprt->inet) {
 		struct sock *sk = sock->sk;
 
-	if (xprt->inet)
-		return;
-
 		write_lock_bh(&sk->sk_callback_lock);
+
 		sk->sk_user_data = xprt;
 		xprt->old_data_ready = sk->sk_data_ready;
 		xprt->old_state_change = sk->sk_state_change;
 		xprt->old_write_space = sk->sk_write_space;
-	if (xprt->prot == IPPROTO_UDP) {
 		sk->sk_data_ready = xs_udp_data_ready;
 		sk->sk_write_space = xs_udp_write_space;
 		sk->sk_no_check = UDP_CSUM_NORCV;
+
 		xprt_set_connected(xprt);
-	} else {
-		tcp_sk(sk)->nonagle = 1;	/* disable Nagle's algorithm */
-		sk->sk_data_ready = xs_tcp_data_ready;
-		sk->sk_state_change = xs_tcp_state_change;
-		sk->sk_write_space = xs_tcp_write_space;
-		xprt_clear_connected(xprt);
-	}
 
 		/* Reset to new socket */
 		xprt->sock = sock;
 		xprt->inet = sk;
-	write_unlock_bh(&sk->sk_callback_lock);
 
-	return;
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+	xs_set_buffer_size(xprt);
+	status = 0;
+out:
+	xprt_wake_pending_tasks(xprt, status);
+	xprt_clear_connecting(xprt);
 }
 
 /**
- * xs_connect_worker - try to connect a socket to a remote endpoint
+ * xs_tcp_connect_worker - connect a TCP socket to a remote endpoint
  * @args: RPC transport to connect
  *
  * Invoked by a work queue tasklet.
  */
-static void xs_connect_worker(void *args)
+static void xs_tcp_connect_worker(void *args)
 {
 	struct rpc_xprt *xprt = (struct rpc_xprt *)args;
 	struct socket *sock = xprt->sock;
-	int status = -EIO;
+	int err, status = -EIO;
 
 	if (xprt->shutdown || xprt->addr.sin_port == 0)
 		goto out;
 
-	dprintk("RPC:      xs_connect_worker xprt %p\n", xprt);
+	dprintk("RPC:      xs_tcp_connect_worker for xprt %p\n", xprt);
 
-	/*
-	 * Start by resetting any existing state
-	 */
+	/* Start by resetting any existing socket state */
 	xs_close(xprt);
-	sock = xs_create(xprt, xprt->prot, xprt->resvport);
-	if (sock == NULL) {
-		/* couldn't create socket or bind to reserved port;
-		 * this is likely a permanent error, so cause an abort */
+
+	if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
+		dprintk("RPC:      can't create TCP transport socket (%d).\n", -err);
 		goto out;
 	}
-	xs_bind(xprt, sock);
-	xs_set_buffer_size(xprt);
 
-	status = 0;
-	if (!xprt->stream)
+	if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
+		sock_release(sock);
 		goto out;
+	}
 
-	/*
-	 * Tell the socket layer to start connecting...
-	 */
+	if (!xprt->inet) {
+		struct sock *sk = sock->sk;
+
+		write_lock_bh(&sk->sk_callback_lock);
+
+		sk->sk_user_data = xprt;
+		xprt->old_data_ready = sk->sk_data_ready;
+		xprt->old_state_change = sk->sk_state_change;
+		xprt->old_write_space = sk->sk_write_space;
+		sk->sk_data_ready = xs_tcp_data_ready;
+		sk->sk_state_change = xs_tcp_state_change;
+		sk->sk_write_space = xs_tcp_write_space;
+		tcp_sk(sk)->nonagle = 1;
+
+		xprt_clear_connected(xprt);
+
+		/* Reset to new socket */
+		xprt->sock = sock;
+		xprt->inet = sk;
+
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+
+	/* Tell the socket layer to start connecting... */
 	status = sock->ops->connect(sock, (struct sockaddr *) &xprt->addr,
 			sizeof(xprt->addr), O_NONBLOCK);
 	dprintk("RPC: %p  connect status %d connected %d sock state %d\n",
@@ -959,7 +975,9 @@ static void xs_connect(struct rpc_task *task)
 {
 	struct rpc_xprt *xprt = task->tk_xprt;
 
-	if (!xprt_test_and_set_connecting(xprt)) {
+	if (xprt_test_and_set_connecting(xprt))
+		return;
+
 	if (xprt->sock != NULL) {
 		dprintk("RPC:      xs_connect delayed xprt %p\n", xprt);
 		schedule_delayed_work(&xprt->connect_worker,
@@ -967,11 +985,11 @@ static void xs_connect(struct rpc_task *task)
 	} else {
 		dprintk("RPC:      xs_connect scheduled xprt %p\n", xprt);
 		schedule_work(&xprt->connect_worker);
+
 		/* flush_scheduled_work can sleep... */
 		if (!RPC_IS_ASYNC(task))
 			flush_scheduled_work();
 	}
-	}
 }
 
 static struct rpc_xprt_ops xs_ops = {
@@ -1013,7 +1031,7 @@ int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	/* XXX: header size can vary due to auth type, IPv6, etc. */
 	xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);
 
-	INIT_WORK(&xprt->connect_worker, xs_connect_worker, xprt);
+	INIT_WORK(&xprt->connect_worker, xs_udp_connect_worker, xprt);
 
 	xprt->ops = &xs_ops;
 
@@ -1052,7 +1070,7 @@ int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
 	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
 	xprt->max_payload = (1U << 31) - 1;
 
-	INIT_WORK(&xprt->connect_worker, xs_connect_worker, xprt);
+	INIT_WORK(&xprt->connect_worker, xs_tcp_connect_worker, xprt);
 
 	xprt->ops = &xs_ops;