[PATCH] selftests net: additional fix for kselftest net build error

[Andrea Righi]

We need to make sure that bpf_helpers.h is properly generated when
building the net kselftest, otherwise we get this build error:

 $ make -C tools/testing/selftests/net
 ...
 bpf/nat6to4.c:43:10: fatal error: 'bpf/bpf_helpers.h' file not found
          ^~~~~~~~~~~~~~~~~~~
 1 error generated.

Fix by adding a make dependency on tools/lib/bpf/bpf_helper_defs.h.

Moreover, re-add the include that was initially added by commit
cf67838c4422 ("selftests net: fix bpf build error"), otherwise we won't
be able to properly include bpf_helpers.h.

Fixes: 7b92aa9e6135 ("selftests net: fix kselftest net fatal error")
Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
---
 tools/testing/selftests/net/bpf/Makefile | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/bpf/Makefile b/tools/testing/selftests/net/bpf/Makefile
index 8ccaf8732eb2..cc6579e154eb 100644
--- a/tools/testing/selftests/net/bpf/Makefile
+++ b/tools/testing/selftests/net/bpf/Makefile
@@ -2,11 +2,15 @@
 
 CLANG ?= clang
 CCINCLUDE += -I../../bpf
+CCINCLUDE += -I../../../lib
 CCINCLUDE += -I../../../../lib
 CCINCLUDE += -I../../../../../usr/include/
 
+bpf_helper_defs.h:
+	@make OUTPUT=./ -C $(OUTPUT)/../../../../tools/lib/bpf bpf_helper_defs.h
+
 TEST_CUSTOM_PROGS = $(OUTPUT)/bpf/nat6to4.o
-all: $(TEST_CUSTOM_PROGS)
+all: bpf_helper_defs.h $(TEST_CUSTOM_PROGS)
 
 $(OUTPUT)/%.o: %.c
 	$(CLANG) -O2 -target bpf -c $< $(CCINCLUDE) -o $@
-- 
2.37.2