Re: [PATCH 2/3] staging: greybus: use inline function for macros

Julia Lawall
2023-03-21T16:36:04Z

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On Tue, 21 Mar 2023, Uwe Kleine-König wrote:

> On Tue, Mar 21, 2023 at 04:59:49PM +0100, Julia Lawall wrote:
> >
> >
> > On Tue, 21 Mar 2023, Uwe Kleine-König wrote:
> >
> > > Hello,
> > >
> > > just some nitpicks:
> > >
> > > On Tue, Mar 21, 2023 at 01:04:33AM +0200, Menna Mahmoud wrote:
> > > > Convert `to_gbphy_dev` and `to_gbphy_driver` macros into a
> > > > static inline function.
> > > >
> > > > it is not great to have macro that use `container_of` macro,
> > >
> > > s/it/It/; s/macro/macros/; s/use/use the/;
> > >
> > > > because from looking at the definition one cannot tell what type
> > > > it applies to.
> > > > [...]
> > > > -#define to_gbphy_dev(d) container_of(d, struct gbphy_device, dev)
> > > > +static inline struct gbphy_device *to_gbphy_dev(const struct device *d)
> > >
> > > drivers/staging/greybus/gbphy.c always passes a variable named
> > > "dev" to this macro. So I'd call the parameter "dev", too, instead of
> > > "d". This is also a more typical name for variables of that type.
> >
> > I argued against that. Because then there are two uses of dev
> > in the argument of container_of, and they refer to completely different
> > things. It's true that by the way container_of works, it's fine, but it
> > may be misleading.
>
> Hmm, that seems to be subjective, but I have less problems with that
> than with using "d" for a struct device (or a struct device_driver).
> I'd even go so far as to consider it nice if they are identical.
>
> Maybe that's because having the first and third argument identical is
> quite common:
>
> $ git grep -P 'container_of\((?<ident>[A-Za-z_0-9-]*)\s*,[^,]*,\s*\g{ident}\s*\)' | wc -l
> 5940
>
> which is >44% of all the usages
>
> $ git grep -P 'container_of\((?<ident>[A-Za-z_0-9-]*)\s*,[^,]*,\s*(?&ident)\s*\)' | wc -l
> 13362

OK, if people like that, then why not. But it's dangerous if the call to
container_of is in a macro, rather than in a function.

julia