Re: [PATCH 2/8] selftests/bpf: build bench.o for any $(OUTPUT)

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Cc: bpf <bpf@vger.kernel.org>, Jiri Benc <jbenc@redhat.com>,
	Jiri Olsa <jolsa@redhat.com>, Andrii Nakryiko <andriin@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [PATCH 2/8] selftests/bpf: build bench.o for any $(OUTPUT)
Date: Tue, 26 May 2020 15:13:36 -0700	[thread overview]
Message-ID: <CAEf4BzZb021L2Dyvp_6HN_rRqt6tOj4Tjpq4J7Nd8FpPV28rGQ@mail.gmail.com> (raw)
In-Reply-To: <20200522041310.233185-3-yauheni.kaliuta@redhat.com>

On Thu, May 21, 2020 at 9:14 PM Yauheni Kaliuta
<yauheni.kaliuta@redhat.com> wrote:
>
> bench.o is produced by implicit rule only if it's built in the same
> directory where bench.c is located. If OUTPUT points somewhere else,
> build fails.
>
> Make an explicit rule for it (factor out common part).
> Add bench.c as a dependency to make it source for CC.

If that's the case, then the similar problem would happen to
test_l4lb_noinline.o, test_xdp_noinline.o, and flow_dissector_load.o,
at least. Let's fix the implicit rule (or define our own, but generic
one), instead of ad-hoc fixing it for bench.o only.

>
> Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
> ---
>  tools/testing/selftests/bpf/Makefile | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 09700db35c2d..f0b7d41ed6dd 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -243,6 +243,11 @@ define GCC_BPF_BUILD_RULE
>         $(BPF_GCC) $3 $4 -O2 -c $1 -o $2
>  endef
>
> +define COMPILE_C_RULE
> +       $(call msg,CC,,$@)
> +       $(CC) $(CFLAGS) -c $(filter %.c,$^) $(LDLIBS) -o $@
> +endef
> +
>  SKEL_BLACKLIST := btf__% test_pinning_invalid.c test_sk_assign.c
>
>  # Set up extra TRUNNER_XXX "temporary" variables in the environment (relies on
> @@ -409,11 +414,11 @@ $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
>
>  # Benchmark runner
>  $(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h
> -       $(call msg,CC,,$@)
> -       $(CC) $(CFLAGS) -c $(filter %.c,$^) $(LDLIBS) -o $@
> +       $(COMPILE_C_RULE)
>  $(OUTPUT)/bench_rename.o: $(OUTPUT)/test_overhead.skel.h
>  $(OUTPUT)/bench_trigger.o: $(OUTPUT)/trigger_bench.skel.h
> -$(OUTPUT)/bench.o: bench.h testing_helpers.h
> +$(OUTPUT)/bench.o: bench.c bench.h testing_helpers.h
> +       $(COMPILE_C_RULE)
>  $(OUTPUT)/bench: LDLIBS += -lm
>  $(OUTPUT)/bench: $(OUTPUT)/bench.o $(OUTPUT)/testing_helpers.o \
>                  $(OUTPUT)/bench_count.o \
> --
> 2.26.2
>