selftests/bpf: BPF object files should depend only on libbpf headers

There is no need to re-build BPF object files if any of the sources of libbpf
change. So record more precise dependency only on libbpf/bpf_*.h headers. This
eliminates unnecessary re-builds.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200820231250.1293069-2-andriin@fb.com

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index a83b582..09657d0 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -316,7 +316,7 @@ $(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.o:                         \
                     $(TRUNNER_BPF_PROGS_DIR)/%.c                       \
                     $(TRUNNER_BPF_PROGS_DIR)/*.h                       \
                     $$(INCLUDE_DIR)/vmlinux.h                          \
-                    $$(BPFOBJ) | $(TRUNNER_OUTPUT)
+                    $(wildcard $(BPFDIR)/bpf_*.h) | $(TRUNNER_OUTPUT)
        $$(call $(TRUNNER_BPF_BUILD_RULE),$$<,$$@,                      \
                                          $(TRUNNER_BPF_CFLAGS),        \
                                          $(TRUNNER_BPF_LDFLAGS))