[alsa-devel] [PATCH 41/45] include/uapi/sound/emu10k1.h: hide gpr_valid, tram_valid and code_valid in userspace

[Takashi Iwai]

At Wed, 11 Mar 2015 10:46:29 +0100,
Arnd Bergmann wrote:
> 
> On Wednesday 11 March 2015 07:11:18 Takashi Iwai wrote:
> > At Wed, 11 Mar 2015 03:22:04 +0200,
> > Mikko Rapeli wrote:
> > > 
> > > On Tue, Feb 17, 2015 at 07:27:38AM +0100, Takashi Iwai wrote:
> > > > At Tue, 17 Feb 2015 00:05:44 +0100,
> > > > Mikko Rapeli wrote:
> > > > > 
> > > > > The DECLARE_BITMAP macro is not available in userspace headers.
> > > > > Fixes userspace compile error:
> > > > > error: expected specifier-qualifier-list before ‘DECLARE_BITMAP’
> > > > 
> > > > It's nonsense.  This results in an incompatible structure, thus ABI
> > > > would be broken completely (actually this will break the compile of
> > > > ld10k1).
> > > 
> > > None of the exported headers after 'make headers_install' have definition
> > > of DECLARE_BITMAP macro. It is defined in include/linux/types.h which is
> > > different from include/uapi/linux/types.h and missing this definition and
> > > a few other things.
> > > 
> > > One option would be add DECLARE_BITMAP macro to include/uapi/linux/types.h
> > > and add include/linux/bitops.h to uapi.
> > > 
> > > Thoughts?
> > 
> > Are there any other headers like that?  If this is the only one, leave
> > it as is.  The only program that reads this are some alsa-tools ones
> > and they have already own DECLARE_BITMAP() definition.  Adding the
> > extra definition here will even break the compilation out of sudden.
> 
> I think it's a worthy goal to have the header files be compilable
> standalone,

In general yes, but this case is very minor issue:
- the file in question is for a hardware device-specific data
  definition,
- there are only two programs read this file, both can be built
  properly,
- and the device and the programs are very old, modifying such need
  extra care.

> but I don't think we should make the DECLARE_BITMAP()
> macro globally visible in user space, in particular because it will
> clash with every instance in which user space has a macro of the
> same name.
> 
> What we could do here is to add a private copy of the macro to emu10k1.h
> under a different name, such as __EMU10K1_DECLARE_BITMAP().

Yes, it's a better option.


thanks,

Takashi