On Wed, Feb 19, 2020 at 11:52:39AM +0100, Johan Hovold wrote:
> On Thu, Feb 13, 2020 at 10:16:00AM +0100, Uwe Kleine-König wrote:
> > From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> >
> > Usage is as follows:
> >
> > myled=ledname
> > tty=ttyS0
> >
> > echo tty > /sys/class/leds/$myled/trigger
> > cat /sys/class/tty/$tty/dev > /sys/class/leds/$myled/dev
> >
> > . When this new trigger is active it periodically checks the tty's
> > statistics and when it changed since the last check the led is flashed
> > once.
> >
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> > ---
>
> > +static ssize_t dev_store(struct device *dev,
> > + struct device_attribute *attr, const char *buf,
> > + size_t size)
> > +{
> > + struct ledtrig_tty_data *trigger_data = led_trigger_get_drvdata(dev);
> > + struct tty_struct *tty;
> > + dev_t d;
> > + int ret;
> > +
> > + if (size == 0 || (size == 1 && buf[0] == '\n')) {
> > + tty = NULL;
> > + } else {
> > + ret = kstrtodev_t(buf, &d);
> > + if (ret < 0)
> > + return ret;
> > +
> > + tty = tty_kopen_shared(d);
>
> I really don't have time to look at this, but having the led-trigger
> keep the port open looks fundamentally broken (consider modem-control
> signals, power, etc).
If I understand correctly calling tty_kopen_shared() doesn't open the
device, just keep it referenced which prevents it to disappear. Unless I
miss something it doesn't result in the tty's .open() being called.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
