[PATCH net-next v1] bpf: Rebuild bpf.o for any dependency update

[MickaÃl SalaÃn]

This is needed to force a rebuild of bpf.o when one of its dependencies
(e.g. uapi/linux/bpf.h) is updated.

Add a phony target.

Signed-off-by: MickaÃl SalaÃn <mic@xxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/Makefile | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index a35f564f66a1..c7816fe60feb 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -1,13 +1,24 @@
-CFLAGS += -Wall -O2 -lcap -I../../../include/uapi -I../../../lib
+LIBDIR := ../../../lib
+BPFOBJ := $(LIBDIR)/bpf/bpf.o
+
+CFLAGS += -Wall -O2 -lcap -I../../../include/uapi -I$(LIBDIR)
 
 test_objs = test_verifier test_tag test_maps test_lru_map test_lpm_map
 
 TEST_PROGS := $(test_objs) test_kmod.sh
 TEST_FILES := $(test_objs)
 
+.PHONY: all clean force
+
 all: $(test_objs)
 
-$(test_objs): ../../../lib/bpf/bpf.o
+# force a rebuild of BPFOBJ when its dependencies are updated
+force:
+
+$(BPFOBJ): force
+	$(MAKE) -C $(dir $(BPFOBJ))
+
+$(test_objs): $(BPFOBJ)
 
 include ../lib.mk
 
-- 
2.11.0