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

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

On Tue, Dec 1, 2020 at 10:20 AM Johan Hovold <johan@...nel.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@...nel.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