Re: [PATCH 2/5] serial: core: add sysfs attribute to suppress ready signalling on open

From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	"Mychaela N . Falconia" <falcon@freecalypso.org>,
	"open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
	USB <linux-usb@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/5] serial: core: add sysfs attribute to suppress ready signalling on open
Date: Tue, 1 Dec 2020 12:55:54 +0200	[thread overview]
Message-ID: <CAHp75VfQud=QxwZyhYRU9mtNvrudj0tS6LOuutfJDVdv=-ptXw@mail.gmail.com> (raw)
In-Reply-To: <X8X9B1jYujUIWXaK@localhost>

On Tue, Dec 1, 2020 at 10:20 AM Johan Hovold <johan@kernel.org> wrote:
> On Mon, Nov 30, 2020 at 08:27:54PM +0200, Andy Shevchenko wrote:
> > On Mon, Nov 30, 2020 at 5:42 PM Johan Hovold <johan@kernel.org> wrote:

> > > +       ret = kstrtouint(buf, 0, &val);
> > > +       if (ret)
> > > +               return ret;
> >
> > > +       if (val > 1)
> > > +               return -EINVAL;
> >
> > Can't we utilise kstrtobool() instead?
>
> I chose not to as kstrtobool() results in a horrid interface. To many
> options to do the same thing and you end up with confusing things like
> "0x01" being accepted but treated as false (as only the first character
> is considered).

And this is perfectly fine. 0x01 is not boolean.

> Not sure how that ever made it into sysfs code...
>
> The attribute is read back as "0" or "1" and those are precisely the
> values that can be written back (well, modulo radix).

So, how does it affect the kstrtobool() interface?
You read back 0 and 1 and they are pretty much accepted by it.

> It's not relevant in this case, but tight control over the inputs also
> allows for extending the range later.

And kstrtobool() does it. So I don't see any difference except a few
less lines of code and actually *stricter* rules than kstrtouint()
has.

-- 
With Best Regards,
Andy Shevchenko