On Tue, Dec 01, 2020 at 12:55:54PM +0200, Andy Shevchenko wrote: > On Tue, Dec 1, 2020 at 10:20 AM Johan Hovold <johan@xxxxxxxxxx> 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@xxxxxxxxxx> 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. 0x01 is 1 and is generally treated as boolean true as you know. So why should a sysfs-interface accept it as valid input and treat it as false? That's just bad design. > > 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. You miss the point; kstrobool accepts "12" today and treats it as true. You cannot extend such an interface to later accept a larger range than 0 and 1 as you didn't return an error for "12" from the start (as someone might now rely on "12" being treated as "1"). Johan
