libbpf: add error reporting in XDP

2018-02-03T01:53:48Z

Parse netlink ext attribute to get the error message returned by the card. Code is partially take from libnl. We add netlink.h to the uapi include of tools. And we need to avoid include of userspace netlink header to have a successful build of sample so nlattr.h has a define to avoid the inclusion. Using a direct define could have been an issue as NLMSGERR_ATTR_MAX can change in the future. We also define SOL_NETLINK if not defined to avoid to have to copy socket.h for a fixed value. Signed-off-by: Eric Leblond Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov

kernel/tools/lib/bpf/nlattr.c, branch linux-4.16.y

libbpf: add error reporting in XDP