Re: [PATCH] uapi glibc compat: fix cases where glibc net/if.h is included before linux/if.h

[Mikko Rapeli]

(Adding libc-alpha list, review of https://lkml.org/lkml/2016/2/7/89 )

On Wed, Feb 17, 2016 at 10:46:20AM -0500, David Miller wrote:
> From: Mikko Rapeli <mikko.rapeli@xxxxxx>
> Date: Sun,  7 Feb 2016 16:03:21 +0200
> 
> > @@ -68,6 +72,8 @@
> >   * @IFF_ECHO: echo sent packets. Volatile.
> >   */
> >  enum net_device_flags {
> > +/* for compatibility with glibc net/if.h */
> > +#if __UAPI_DEF_IF_NET_DEVICE_FLAGS
> >  	IFF_UP				= 1<<0,  /* sysfs */
> >  	IFF_BROADCAST			= 1<<1,  /* volatile */
> >  	IFF_DEBUG			= 1<<2,  /* sysfs */
> > @@ -84,11 +90,14 @@ enum net_device_flags {
> >  	IFF_PORTSEL			= 1<<13, /* sysfs */
> >  	IFF_AUTOMEDIA			= 1<<14, /* sysfs */
> >  	IFF_DYNAMIC			= 1<<15, /* sysfs */
> > +#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS */
> >  	IFF_LOWER_UP			= 1<<16, /* volatile */
> >  	IFF_DORMANT			= 1<<17, /* volatile */
> >  	IFF_ECHO			= 1<<18, /* volatile */
> >  };
> 
> This is going to get messy is IFF_LOWER_UP, IFF_DORMANT, and IFF_ECHO
> get added the the glibc header.  Why not just handle it now with
> another __UAPI_DEF_FOO guard so that the additions to net/if.h can
> deal with this case too.

Do you mean that the enum should be protected with a single guard or
should I have one guard for current conflicts and one for the future
if glibc headers include IFF_LOWER_UP and others?

-Mikko