On Tue, Aug 23, 2016 at 10:03 AM, Frans Klaver <franskla...@gmail.com> wrote: > On Tue, Aug 23, 2016 at 9:05 AM, David Miller <da...@davemloft.net> wrote: >> From: Frans Klaver <franskla...@gmail.com> >> Date: Tue, 23 Aug 2016 09:03:20 +0200 >> >>> On Tue, Aug 23, 2016 at 1:30 AM, David Miller <da...@davemloft.net> wrote: >>>> From: Mikko Rapeli <mikko.rap...@iki.fi> >>>> Date: Mon, 22 Aug 2016 20:32:44 +0200 >>>> >>>>> Fixes userspace compiler error: >>>>> >>>>> error: ‘IFNAMSIZ’ undeclared here (not in a function) >>>>> >>>>> Suggested by Frans Klaver <franskla...@gmail.com> on lkml message >>>>> <20150530195223.ga15...@bugger.home>. >>>>> >>>>> Signed-off-by: Mikko Rapeli <mikko.rap...@iki.fi> >>>> >>>> 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.
