Re: [PATCH] staging: greybus: eclose macro in a do - while loop

[Menna Mahmoud]

On ١١‏/٣‏/٢٠٢٣ ٢١:١٠, Alex Elder wrote:
> On 3/11/23 7:59 AM, Menna Mahmoud wrote:
> > " ERROR: Macros with multiple statements should be enclosed in a do -
> > while loop"
> >
> > Reported by checkpath.
>
> This is also not an issue that should be "fixed."
>
> If you look at where that macro is expanded, you see
> that its purpose is simply to reduce the possibility
> of some errors by enclosing some much-duplicated code
> in this macro.  The expansion is at the top level of
> the source file, so a "do...while" loop ends up being
> an error.
>
> When looking at the output of checkpatch, assume it's
> giving you clues about problems that one *might* like to
> fix.  Its suggestions are most often reasonable, but in
> some cases (like this one) it's just not smart enough
> to recognize the problem that comes from following its
> advice.
>
> Make sure you understand exactly what happens when
> you make a change.  That means understanding the
> code, and then it means ensuring that the fix passes
> at least a compile test, and if possible an actual
> execution test.
>
>                     -Alex


I see, Thanks Alex for explaining. I will check the code before making 
any change.

Menna


> > do loop with the conditional expression set to a constant
> > value of zero (0).This creates a loop that
> > will execute exactly one time.This is a coding idiom that
> > allows a multi-line macro to be used anywhere
> > that a single statement can be used.
> >
> > So, enclose `gb_loopback_stats_attrs` macro in do - while (0) to
> > fix checkpath error
> >
> > Signed-off-by: Menna Mahmoud <eng.mennamahmoud.mm@xxxxxxxxx>
> > ---
> >   drivers/staging/greybus/loopback.c | 10 ++++++----
> >   1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/staging/greybus/loopback.c 
> > b/drivers/staging/greybus/loopback.c
> > index 1a61fce98056..e86d50638cb5 100644
> > --- a/drivers/staging/greybus/loopback.c
> > +++ b/drivers/staging/greybus/loopback.c
> > @@ -162,10 +162,12 @@ static ssize_t name##_avg_show(struct device 
> > *dev,        \
> >   }                                    \
> >   static DEVICE_ATTR_RO(name##_avg)
> >   -#define gb_loopback_stats_attrs(field)                \
> > -    gb_loopback_ro_stats_attr(field, min, u);        \
> > -    gb_loopback_ro_stats_attr(field, max, u);        \
> > -    gb_loopback_ro_avg_attr(field)
> > +#define gb_loopback_stats_attrs(field)                    \
> > +    do { \
> > +        gb_loopback_ro_stats_attr(field, min, u);        \
> > +        gb_loopback_ro_stats_attr(field, max, u);        \
> > +        gb_loopback_ro_avg_attr(field);                \
> > +    } while (0)
> >     #define gb_loopback_attr(field, type)                    \
> >   static ssize_t field##_show(struct device *dev, \