The BPF Makefile in net/bpf did incorrect path substitution for O=dir
builds, e.g.
make O=/tmp/kselftest headers
make O=/tmp/kselftest -C tools/testing/selftests
would fail in selftest builds [1] net/ with
clang-16: error: no such file or directory: 'kselftest/net/bpf/nat6to4.c'
clang-16: error: no input files
Add a pattern prerequisite and an order-only-prerequisite (for
creating the directory), to resolve the issue.
[1] https://lore.kernel.org/all/202212060009.34CkQmCN-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 837a3d66d6 ("selftests: net: Add cross-compilation support for BPF programs")
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20221206102838.272584-1-bjorn@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
17961a37ce