glibc's net/if.h contains copies of definitions from linux/if.h and these conflict and cause build failures if both files are included by application source code. Changes in uapi headers, which fixed header file dependencies to include linux/if.h when it was needed, e.g. commit 1ffad83d, made the net/if.h and linux/if.h incompatibilities visible as build failures for userspace applications like iproute2 and xtables-addons. This patch fixes compile errors when glibc net/if.h is included before linux/if.h: ./linux/if.h:99:21: error: redeclaration of enumerator ‘IFF_NOARP’ ./linux/if.h:98:23: error: redeclaration of enumerator ‘IFF_RUNNING’ ./linux/if.h:97:26: error: redeclaration of enumerator ‘IFF_NOTRAILERS’ ./linux/if.h:96:27: error: redeclaration of enumerator ‘IFF_POINTOPOINT’ ./linux/if.h:95:24: error: redeclaration of enumerator ‘IFF_LOOPBACK’ ./linux/if.h:94:21: error: redeclaration of enumerator ‘IFF_DEBUG’ ./linux/if.h:93:25: error: redeclaration of enumerator ‘IFF_BROADCAST’ ./linux/if.h:92:19: error: redeclaration of enumerator ‘IFF_UP’ ./linux/if.h:252:8: error: redefinition of ‘struct ifconf’ ./linux/if.h:203:8: error: redefinition of ‘struct ifreq’ ./linux/if.h:169:8: error: redefinition of ‘struct ifmap’ ./linux/if.h:107:23: error: redeclaration of enumerator ‘IFF_DYNAMIC’ ./linux/if.h:106:25: error: redeclaration of enumerator ‘IFF_AUTOMEDIA’ ./linux/if.h:105:23: error: redeclaration of enumerator ‘IFF_PORTSEL’ ./linux/if.h:104:25: error: redeclaration of enumerator ‘IFF_MULTICAST’ ./linux/if.h:103:21: error: redeclaration of enumerator ‘IFF_SLAVE’ ./linux/if.h:102:22: error: redeclaration of enumerator ‘IFF_MASTER’ ./linux/if.h:101:24: error: redeclaration of enumerator ‘IFF_ALLMULTI’ ./linux/if.h:100:23: error: redeclaration of enumerator ‘IFF_PROMISC’ The cases where linux/if.h is included before net/if.h need a similar fix in the glibc side, or the order of include files can be changed userspace code as a workaround. This change was tested in x86 userspace on Debian unstable with scripts/headers_compile_test.sh: $ make headers_install && \ cd usr/include && ../../scripts/headers_compile_test.sh -l -k ... cc -Wall -c -nostdinc -I /usr/lib/gcc/i586-linux-gnu/5/include -I /usr/lib/gcc/i586-linux-gnu/5/include-fixed -I . -I /home/mcfrisk/src/linux-2.6/usr/headers_compile_test_include.2uX2zH -I /home/mcfrisk/src/linux-2.6/usr/headers_compile_test_include.2uX2zH/i586-linux-gnu -o /dev/null ./linux/if.h_libc_before_kernel.h PASSED libc before kernel test: ./linux/if.h Reported-by: Jan Engelhardt <jengelh@inai.de> Reported-by: Josh Boyer <jwboyer@fedoraproject.org> Reported-by: Stephen Hemminger <shemming@brocade.com> Reported-by: Waldemar Brodkorb <mail@waldemar-brodkorb.de> Cc: Gabriel Laskar <gabriel@lse.epita.fr> Signed-off-by: Mikko Rapeli <mikko.rapeli@iki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>