For older glibc ~2.17, #include'ing both linux/if.h and net/if.h
fails due to complaints about redefinition of interface flags:
CC net.o
In file included from net.c:13:0:
/usr/include/linux/if.h:71:2: error: redeclaration of enumerator ‘IFF_UP’
IFF_UP = 1<<0, /* sysfs */
^
/usr/include/net/if.h:44:5: note: previous definition of ‘IFF_UP’ was here
IFF_UP = 0x1, /* Interface is up. */
The issue was fixed in kernel headers in [1], but since compilation
of net.c picks up system headers the problem can recur.
Dropping #include <linux/if.h> resolves the issue and it is
not needed for compilation anyhow.
[1] https://lore.kernel.org/netdev/1461512707-23058-1-git-send-email-mikko.rapeli__34748.27880641$1462831734$gmane$org@iki.fi/
Fixes: f6f3bac08f ("tools/bpf: bpftool: add net support")
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/1609948746-15369-1-git-send-email-alan.maguire@oracle.com
6f02b540d7