On 03/16/2017 09:26 AM, Mikko Rapeli wrote: > On Thu, Mar 16, 2017 at 07:59:12AM +0000, David Woodhouse wrote: >> On Sun, 2017-03-12 at 23:00 +0100, Hauke Mehrtens wrote: >>> __USE_MISC is glibc specific and not available in musl libc. Only do >>> this check when glibc is used. This fixes a problem with musl libc. >>> ... >>> -/* Coordinate with glibc net/if.h header. */ >>> -#if defined(_NET_IF_H) && defined(__USE_MISC) >>> +/* Coordinate with libc net/if.h header. */ >>> +#if defined(_NET_IF_H) && (!defined(__GLIBC__) || defined(__USE_MISC)) >> >> I *really* don't like building up a plethora of knowledge about >> specific libc implementations in the kernel. As a general rule, if we >> have *anything* that depends on __GLIBC__ then we are Doing It Wrong™. > > Kernel does not depend on glibc but uapi headers check for some defintions > so that userspace code can include both libc and kernel header files > without compiler errors. > > This interface between kernel and libc header files is messy due to long > history of copying header files from kernel to libc implementations etc > and thus this kind of ifdef magic with in depth knowledge of various > libc's defintions is currently unavoidable.
I agree with you David. Should I change my patch? The check for __USE_MISC was added in this commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f0a3fdca794d1e68ae284ef4caefe681f7c18e89 musl does not define it, but still adds the defines which glibc adds when __USE_MISC is set. Hauke
