This is a note to let you know that I've just added the patch titled selftests, bpf: Fix makefile dependencies on libbpf to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: selftests-bpf-fix-makefile-dependencies-on-libbpf.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 491f4f9b5381974f5b920ee50da3435970a46cd3 Author: Jiri Benc <jbenc@xxxxxxxxxx> Date: Mon Sep 27 18:01:36 2021 +0200 selftests, bpf: Fix makefile dependencies on libbpf [ Upstream commit d888eaac4fb1df30320bb1305a8f78efe86524c6 ] 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> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Link: https://lore.kernel.org/bpf/ee84ab66436fba05a197f952af23c98d90eb6243.1632758415.git.jbenc@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index f405b20c1e6c..93f1f124ef89 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -374,7 +374,8 @@ $(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))