Re: + procfs-add-vmflags-field-in-smaps-output-v3-fix-2.patch added to -mm tree

[Cyrill Gorcunov <gorcunov@openvz.org>]

On Wed, Oct 24, 2012 at 08:47:46PM +1100, Stephen Rothwell wrote:
> Hi Cyrill,
> 
> On Wed, 24 Oct 2012 12:45:15 +0400 Cyrill Gorcunov <gorcunov@openvz.org> 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?

> 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 ;)

> >  	seq_puts(m, "VmFlags: ");
> >  	for (i = 0; i < BITS_PER_LONG; i++) {
> > -		if (vma->vm_flags & (1 << i))
> > +		if (vma->vm_flags & (1ul << i)) {
> >  			seq_printf(m, "%c%c ",
> >  				   mnemonics[i].l[0],
> >  				   mnemonics[i].l[1]);
> 
> 				   mnemonics[i][0], mnemonics[i][1]
> 
> /me looks for another bike shed :-)

Heh :)