Cannot be restarted after ctrl C

Do you have any idea about why I enter ctrl+ c then the application cannot be restarted and needs to be power off/on?
However I created function to get SIGINT signal from ctrl+ c then call the uart_stop(), the result is the same, the program always hang on "fd = open(dev->filename, O_RDWR | O_NOCTTY);" , seems resource not be released still.

thanks
Webber