serial-uartlite: Spinlock inside the loop.

Better to hold the spinlock as short as possible.
Signed-off-by: Maarten Brock <m.brock@vanmierlo.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/uartlite.c

@@ -193,19 +193,18 @@ static int ulite_transmit(struct uart_port *port, int stat)
 static irqreturn_t ulite_isr(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
-	int busy, n = 0;
+	int stat, busy, n = 0;
 	unsigned long flags;
 
-	spin_lock_irqsave(&port->lock, flags);
 	do {
-		int stat = uart_in32(ULITE_STATUS, port);
+		spin_lock_irqsave(&port->lock, flags);
+		stat = uart_in32(ULITE_STATUS, port);
 		busy  = ulite_receive(port, stat);
 		busy |= ulite_transmit(port, stat);
+		spin_unlock_irqrestore(&port->lock, flags);
 		n++;
 	} while (busy);
 
-	spin_unlock_irqrestore(&port->lock, flags);
-
 	/* work done? */
 	if (n > 1) {
 		tty_flip_buffer_push(&port->state->port);