On Thu, Apr 09, 2015 at 09:28:53AM -0700, Stephen Hemminger wrote:
> On Thu, 9 Apr 2015 10:32:24 +0200
> Adrien Mazarguil <adrien.mazarguil at 6wind.com> wrote:
>
> > >
> > > +#ifdef RTE_LIBRTE_ENIC_DEBUG
> > > #define ENICPMD_FUNC_TRACE() \
> > > RTE_LOG(DEBUG, PMD, "ENICPMD trace: %s\n", __func__)
> > > +#else
> > > +#define ENICPMD_FUNC_TRACE() do {} while (0)
> >
> > How about defining it as (void)0 instead of an empty do/while block?
> >
> > Doing so will prevent warnings if this macro happens to be used in an
> > expression. RTE_LOG() supports it.
>
> I kind of like the Linux printk trick since it then preserves the format
> checking
> even if compiled out.
>
> /*
> * Dummy printk for disabled debugging statements to use whilst maintaining
> * gcc's format and side-effect checking.
> */
> static inline __printf(1, 2)
> int no_printk(const char *fmt, ...)
> {
> return 0;
> }
>
> /* pr_devel() should produce zero code unless DEBUG is defined */
> #ifdef DEBUG
> #define pr_devel(fmt, ...) \
> printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> #else
> #define pr_devel(fmt, ...) \
> no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
> #endif
My only concern with this is that it cannot be done in a ISO C compliant
manner easily.
While "__printf()" can be defined to nothing when dealing with compilers
that do not support extensions, ", ## __VAR_ARGS__" will most likely fail
with -pedantic.
--
Adrien Mazarguil
6WIND
