On Tue, Apr 02, 2019 at 10:05:00AM +0300, Gal Pressman wrote:
> >>>> +#elif defined(DEBUG)
> >>>> +#define ibdev_dbg(__dev, format, args...) \
> >>>> + ibdev_printk(KERN_DEBUG, __dev, format, ##args)
> >>>> +#else
> >>>> +#define ibdev_dbg(__dev, format, args...) \
> >>>> +({ \
> >>>> + if (0) \
> >>>
> >>> Why isn't "empty macro" enough here and we need "if (0)"?
> >>
> >> I was wondering as well :).
> >> This is copied from the netdev_dbg counterpart, my best guess is some kind of
> >> compilation checks in case debug is disabled but I can't even convince myself..
> >
> > It is a trick to get the compiler to do a format & type check even
> > when debug is disabled.
> >
> > Personally I prefer the much clearer non #define version
> >
> > __printf(2, 3)
> > static inline void ibdev_dbg(const struct ib_device *dev, const char
> > *format, ...) {}
> >
> > Instead of the macro tricks.
>
> Wouldn't that lose the format type checking? For example passing a pointer to %d?
No, the static inline has the __printf attribute so the compiler checks it even
though the inline is empty
Jason
