SUNRPC: Don't loop forever in xs_tcp_data_receive()

Ensure that we don't hog the workqueue thread by requeuing the job
every 64 loops.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

net/sunrpc/xprtsock.c

@@ -1526,6 +1526,7 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)
 		.arg.data = xprt,
 	};
 	unsigned long total = 0;
+	int loop;
 	int read = 0;
 
 	mutex_lock(&transport->recv_mutex);
@@ -1534,20 +1535,20 @@ static void xs_tcp_data_receive(struct sock_xprt *transport)
 		goto out;
 
 	/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
-	for (;;) {
+	for (loop = 0; loop < 64; loop++) {
 		lock_sock(sk);
 		read = tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
 		if (read <= 0) {
 			clear_bit(XPRT_SOCK_DATA_READY, &transport->sock_state);
 			release_sock(sk);
-			if (!test_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
-				break;
-		} else {
-			release_sock(sk);
-			total += read;
+			break;
 		}
+		release_sock(sk);
+		total += read;
 		rd_desc.count = 65536;
 	}
+	if (test_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
+		queue_work(xprtiod_workqueue, &transport->recv_worker);
 out:
 	mutex_unlock(&transport->recv_mutex);
 	trace_xs_tcp_data_ready(xprt, read, total);