Deflake TestCloseRead.

The test needs to wait for CreateEndpoint to return before
cleaning up the stack, otherwise if the netstack is slow to
process the final ACK to the handshake the active side of the
connection can race ahead to the end and start tearing down the
stack.

This results in CreateEndpoint failing with a connection
aborted error.

PiperOrigin-RevId: 446515200

pkg/tcpip/adapters/gonet/gonet_test.go

@@ -265,12 +265,14 @@ func TestCloseRead(t *testing.T) {
 		t.Fatalf("AddProtocolAddress(%d, %+v, {}): %s", NICID, protocolAddr, err)
 	}
 
+	done := make(chan struct{})
 	fwd := tcp.NewForwarder(s, 30000, 10, func(r *tcp.ForwarderRequest) {
 		var wq waiter.Queue
 		_, err := r.CreateEndpoint(&wq)
 		if err != nil {
 			t.Fatalf("r.CreateEndpoint() = %v", err)
 		}
+		close(done)
 		// Endpoint will be closed in deferred s.Close (above).
 	})
 
@@ -294,6 +296,12 @@ func TestCloseRead(t *testing.T) {
 	if n, err := c.Write([]byte("abc123")); n != 6 || err != nil {
 		t.Errorf("c.Write() = (%d, %v), want (6, nil)", n, err)
 	}
+
+	select {
+	case <-done:
+	case <-time.After(1 * time.Second):
+		t.Fatalf("timed out waiting for r.CreateEndpoint(...) to complete")
+	}
 }
 
 func TestCloseWrite(t *testing.T) {