SUNRPC: Don't call connect() more than once on a TCP socket

commit 89f4249 upstream.

Avoid socket state races due to repeated calls to ->connect() using the
same socket. If connect() returns 0 due to the connection having
completed, but we are in fact in a closing state, then we may leave the
XPRT_CONNECTING flag set on the transport.

Reported-by: Enrico Scholz <[email protected]>
Fixes: 3be232f ("SUNRPC: Prevent immediate close+reconnect")
Signed-off-by: Trond Myklebust <[email protected]>
[meenashanmugam: Backported to 5.10: Fixed merge conflict in xs_tcp_setup_socket]
Signed-off-by: Meena Shanmugam <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Trond Myklebust

include/linux/sunrpc/xprtsock.h

@@ -89,5 +89,6 @@ struct sock_xprt {
 #define XPRT_SOCK_WAKE_WRITE	(5)
 #define XPRT_SOCK_WAKE_PENDING	(6)
 #define XPRT_SOCK_WAKE_DISCONNECT	(7)
+#define XPRT_SOCK_CONNECT_SENT	(8)
 
 #endif /* _LINUX_SUNRPC_XPRTSOCK_H */

net/sunrpc/xprtsock.c

@@ -2260,10 +2260,14 @@ static void xs_tcp_setup_socket(struct work_struct *work)
 	struct rpc_xprt *xprt = &transport->xprt;
 	int status = -EIO;
 
-	if (!sock) {
-		sock = xs_create_sock(xprt, transport,
-				xs_addr(xprt)->sa_family, SOCK_STREAM,
-				IPPROTO_TCP, true);
+	if (xprt_connected(xprt))
+		goto out;
+	if (test_and_clear_bit(XPRT_SOCK_CONNECT_SENT,
+			       &transport->sock_state) ||
+	    !sock) {
+		xs_reset_transport(transport);
+		sock = xs_create_sock(xprt, transport, xs_addr(xprt)->sa_family,
+				      SOCK_STREAM, IPPROTO_TCP, true);
 		if (IS_ERR(sock)) {
 			status = PTR_ERR(sock);
 			goto out;
@@ -2294,6 +2298,8 @@ static void xs_tcp_setup_socket(struct work_struct *work)
 		break;
 	case 0:
 	case -EINPROGRESS:
+		set_bit(XPRT_SOCK_CONNECT_SENT, &transport->sock_state);
+		fallthrough;
 	case -EALREADY:
 		xprt_unlock_connect(xprt, transport);
 		return;
@@ -2345,13 +2351,9 @@ static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task)
 
 	WARN_ON_ONCE(!xprt_lock_connect(xprt, task, transport));
 
-	if (transport->sock != NULL && !xprt_connecting(xprt)) {
+	if (transport->sock != NULL) {
 		dprintk("RPC:       xs_connect delayed xprt %p for %lu "
-				"seconds\n",
-				xprt, xprt->reestablish_timeout / HZ);
-
-		/* Start by resetting any existing state */
-		xs_reset_transport(transport);
+			"seconds\n", xprt, xprt->reestablish_timeout / HZ);
 
 		delay = xprt_reconnect_delay(xprt);
 		xprt_reconnect_backoff(xprt, XS_TCP_INIT_REEST_TO);