Re: [PATCH v2 09/12] gpio: sim: new testing module

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

On Thu, Mar 04, 2021 at 09:15:29PM +0100, Bartosz Golaszewski wrote:
> On Thu, Mar 4, 2021 at 2:15 PM Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > On Thu, Mar 04, 2021 at 11:24:49AM +0100, Bartosz Golaszewski wrote:
> > > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>

> > > +
> > > +     /*
> > > +      * FIXME If anyone knows a better way to parse that - please let me
> > > +      * know.
> > > +      */
> >
> > If comma can be replaced with ' ' (space) then why not to use next_arg() from
> > cmdline.c? I.o.w. do you have strong opinion why should we use comma here?
> >
> 
> My opinion is not very strong but I wanted to make the list of names
> resemble what we pass to the gpio-line-names property in device tree.
> Doesn't next_arg() react differently to string of the form: "foo=bar"?

It's ambiguous here.

So, the strings '"foo=bar"' and 'foo=bar' (w/o single quotes!) are indeed
parsed differently, i.e.
	'"foo=bar"' -> 'foo=bar',
while
	"foo=bar" -> 'foo' + 'bar'.

...

> > > +     ida_free(&gpio_sim_ida, id);
> >
> > Isn't it atomic per se? I mean that IDA won't give the same ID until you free
> > it. I.o.w. why is it under the mutex?
> >
> 
> You're right but if we rapidly create and destroy chips we'll be left
> with holes in the numbering (because new devices would be created
> before the IDA numbers are freed, so the driver would take a larger
> number that's currently free). It doesn't hurt but it would look worse
> IMO. Do you have a strong opinion on this?

It's not strong per se, but I would rather follow the 2nd rule of locking:
don't protect something which doesn't need it.

-- 
With Best Regards,
Andy Shevchenko