Re: [PATCH v05 27/72] linux/if.h linux/hdlc/ioctl.h: move IFNAMSIZ definition to hdlc/ioctl.h

[Mikko Rapeli]

On Wed, Aug 24, 2016 at 08:57:21AM +0200, Frans Klaver wrote:
> On Tue, Aug 23, 2016 at 10:03 AM, Frans Klaver <fransklaver@xxxxxxxxx> wrote:
> > On Tue, Aug 23, 2016 at 9:05 AM, David Miller <davem@xxxxxxxxxxxxx> wrote:
> >> From: Frans Klaver <fransklaver@xxxxxxxxx>
> >> Date: Tue, 23 Aug 2016 09:03:20 +0200
> >>
> >>> On Tue, Aug 23, 2016 at 1:30 AM, David Miller <davem@xxxxxxxxxxxxx> wrote:
> >>>> From: Mikko Rapeli <mikko.rapeli@xxxxxx>
> >>>> Date: Mon, 22 Aug 2016 20:32:44 +0200
> >>>>
> >>>>> Fixes userspace compiler error:
> >>>>>
> >>>>> error: âIFNAMSIZâ undeclared here (not in a function)
> >>>>>
> >>>>> Suggested by Frans Klaver <fransklaver@xxxxxxxxx> on lkml message
> >>>>> <20150530195223.GA15645@xxxxxxxxxxx>.
> >>>>>
> >>>>> Signed-off-by: Mikko Rapeli <mikko.rapeli@xxxxxx>
> >>>>
> >>>> IFNAMSIZ has to be in linux/if.h, you aren't explaining why you have
> >>>> to move it to the hdlc header instead of having the hdlc header
> >>>> include linux/if.h
> >>>
> >>> Circular references. linux/if.h includes hdlc/ioctl.h, and has to
> >>> define IFNAMSIZ before doing so.
> >>
> >> That's not acceptable.  Use forward declarations or similar to avoid
> >> the circular dependency.
> >>
> >> IFNAMSIZ belongs in linux/if.h, please keep it there.
> >
> > I went back to one of the previous patch sets, but couldn't find why
> > the circular dependency had to be broken. So if this can be fixed by
> > including linux/if.h instead, I'm all for it.
> 
> Alright, so the core of the 'problem' is that the structs in
> hdlc/ioctl.h are typedefs of anonymous structs, and linux/if.h points
> to those types. We can't really forward declare these structs unless
> we name them, so the proper approach would be to name them and use
> forward declarations in linux/if.h. hdlc/ioctl.h can then include
> linux/if.h. linux/if.h should probably keep including hdlc/ioctl.h to
> keep depending application builds from breaking.

Thanks! I will do this and send a new patch.

-Mikko