led_close Function

The led_close function is defined in led_cdevsw as the d_close operation. Here is its function definition (again):

static int
led_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
{
        int led = dev2unit(dev) & 0xff;
        struct led_softc *sc = dev->si_drv1;

        if (led >= LED_NUM)
                return (ENXIO);

        mtx_lock(&sc->sc_mutex);
      sc->sc_open_mask &= ˜(1 << led);
        mtx_unlock(&sc->sc_mutex);

        return (0);
}

As you can see, this function simply clears sc_open_mask’s led bit (which allows another process to open this device).