Re: [Patch v8 1/6] tty: add new helper function tty_get_tiocm

[Florian Eckert]

On 2023-11-20 08:21, Jiri Slaby wrote:
> On 09. 11. 23, 9:50, Florian Eckert wrote:
> > There is no in-kernel function to get the status register of a tty 
> > device
> > like the TIOCMGET ioctl returns to userspace. Create a new function,
> > tty_get_tiocm(), to obtain the status register that other portions of 
> > the
> > kernel can call if they need this information, and move the existing
> > internal tty_tiocmget() function to use this interface.
> >
> > Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Florian Eckert <fe@xxxxxxxxxx>
> > ---
> >   drivers/tty/tty_io.c | 28 ++++++++++++++++++++++------
> >   include/linux/tty.h  |  1 +
> >   2 files changed, 23 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> > index 06414e43e0b5..e2e93404133e 100644
> > --- a/drivers/tty/tty_io.c
> > +++ b/drivers/tty/tty_io.c
> > @@ -2498,6 +2498,24 @@ static int send_break(struct tty_struct *tty, 
> > unsigned int duration)
> >   	return retval;
> >   }
> >   +/**
> > + * tty_get_tiocm - get tiocm status register
> > + * @tty: tty device
> > + *
> > + * Obtain the modem status bits from the tty driver if the feature
> > + * is supported.
> > + */
> > +int tty_get_tiocm(struct tty_struct *tty)
> > +{
> > +	int retval = -ENOTTY;
> > +
> > +	if (tty->ops->tiocmget)
> > +		retval = tty->ops->tiocmget(tty);
> > +
> > +	return retval;
>
> Why not simply:

I just did it this way because it is also done this way in other 
functions
in this file.

> {
>  if (tty->ops->tiocmget)
>     return tty->ops->tiocmget(tty);
>
>  return -ENOTTY;
> }

Of course, we could also do it this way. If this is the C style for the 
kernel,
then I will change it. Please give me a short feedback whether I should 
change it
and send a v9, or whether it is just a comment from you.

Best regards

Florian