Re: [PATCH bpf-next 4/5] selftests/bpf: silence clang compilation warnings

[Sedat Dilek <sedat.dilek@gmail.com>]

On Sat, Apr 10, 2021 at 6:49 PM Yonghong Song <yhs@fb.com> wrote:
>
> With clang compiler:
>   make -j60 LLVM=1 LLVM_IAS=1  <=== compile kernel
>   make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1
> Some linker flags are not used/effective for some binaries and
> we have warnings like:
>   warning: -lelf: 'linker' input unused [-Wunused-command-line-argument]
>
> We also have warnings like:
>   .../selftests/bpf/prog_tests/ns_current_pid_tgid.c:74:57: note: treat the string as an argument to avoid this
>         if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", strerror(errno)))
>                                                                ^
>                                                                "%s",
>   .../selftests/bpf/test_progs.h:129:35: note: expanded from macro 'CHECK'
>         _CHECK(condition, tag, duration, format)
>                                          ^
>   .../selftests/bpf/test_progs.h:108:21: note: expanded from macro '_CHECK'
>                 fprintf(stdout, ##format);                              \
>                                   ^
> Let us add proper compilation flags to silence the above two kinds of warnings.
>
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---
>  tools/testing/selftests/bpf/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index bbd61cc3889b..a9c0a64a4c49 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -24,6 +24,8 @@ SAN_CFLAGS    ?=
>  CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS)             \
>           -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)          \
>           -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)                      \
> +         -Wno-unused-command-line-argument                             \
> +         -Wno-format-security                                          \

Are both compliler flags available for GCC (I simply don't know or
have checked)?

- Sedat -

>           -Dbpf_prog_load=bpf_prog_test_load                            \
>           -Dbpf_load_program=bpf_test_load_program
>  LDLIBS += -lcap -lelf -lz -lrt -lpthread
> --
> 2.30.2
>