Hi Cyrill, On Wed, 24 Oct 2012 13:59:59 +0400 Cyrill Gorcunov <[email protected]> wrote: > > On Wed, Oct 24, 2012 at 08:47:46PM +1100, Stephen Rothwell wrote: > > > > On Wed, 24 Oct 2012 12:45:15 +0400 Cyrill Gorcunov <[email protected]> > > wrote: > > > > > > static void show_smap_vma_flags(struct seq_file *m, struct > > > vm_area_struct *vma) > > > { > > > +#define __VM_FLAG(_f, _s) [ilog2(_f)] = {(const char [2]){_s}} > > > > I really don't think you need the cast (and it may hide bad usages) or > > the second set of braces. Thus: > > Hi Stephen, could you please elaborate, which bad usage hiding could be there?
I though it might suppress a warning if someone added an entry with a >2
character string, but testing shows that it does not, so that is OK.
There is still no need for the cast, though, or the second set of
braces. The C standard allows fixed length char arrays to be initialised
by string constants and discards the trailing NUL if necessary.
> > Further is there any reason for the struct?
> >
> > #define __VM_FLAG(_f, _s) [ilog2(_f)] = _s
> >
> > static const char mnemonics[BITS_PER_LONG][2] = {
> > ...
> > };
>
> Well, good point, though the benefit of using stucture here
> could be easier way for extension if needed. The compiled result
> is the same as for plain array or structure, so I would rather
> stick with struct here, until contrary proved (I mean it's not
> a problem to update the patch and use array here but I still
> think struct it better in long term). If you guys think that I
> should move it to array -- no problem, i may update ;)
One thing we learn about early (especially working at IBM) is to resist
the temptation to over engineer :-)
--
Cheers,
Stephen Rothwell [email protected]
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