When building bpf selftest with make -j, I'm randomly getting build failures
such as this one:
> In file included from progs/bpf_flow.c:19:
> [...]/tools/testing/selftests/bpf/tools/include/bpf/bpf_helpers.h:11:10: fatal error: 'bpf_helper_defs.h' file not found
> #include "bpf_helper_defs.h"
> ^~~~~~~~~~~~~~~~~~~
The file that fails the build varies between runs but it's always in the
progs/ subdir.
The reason is a missing make dependency on libbpf for the .o files in
progs/. There was a dependency before commit 3ac2e20fba07e but that commit
removed it to prevent unneeded rebuilds. However, that only works if libbpf
has been built already; the 'wildcard' prerequisite does not trigger when
there's no bpf_helper_defs.h generated yet.
Keep the libbpf as an order-only prerequisite to satisfy both goals. It is
always built before the progs/ objects but it does not trigger unnecessary
rebuilds by itself.
Fixes: 3ac2e20fba07e ("selftests/bpf: BPF object files should depend only on libbpf headers")
Signed-off-by: Jiri Benc <jbenc@xxxxxxxxxx>
---
tools/testing/selftests/bpf/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 866531c08e4f..e7c42695dbbf 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -375,7 +375,8 @@ $(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.o: \
$(TRUNNER_BPF_PROGS_DIR)/%.c \
$(TRUNNER_BPF_PROGS_DIR)/*.h \
$$(INCLUDE_DIR)/vmlinux.h \
- $(wildcard $(BPFDIR)/bpf_*.h) | $(TRUNNER_OUTPUT)
+ $(wildcard $(BPFDIR)/bpf_*.h) | $(TRUNNER_OUTPUT) \
+ $$(BPFOBJ)
$$(call $(TRUNNER_BPF_BUILD_RULE),$$<,$$@, \
$(TRUNNER_BPF_CFLAGS))
--
2.18.1
