Re: [PATCH bpf-next v2 09/10] selftests: Remove tools/lib/bpf from include path

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Shuah Khan <shuah@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	linux-rdma@vger.kernel.org,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH bpf-next v2 09/10] selftests: Remove tools/lib/bpf from include path
Date: Wed, 15 Jan 2020 09:22:01 -0800	[thread overview]
Message-ID: <CAEf4BzZ2jAQPKzzp+NhWXbUFcfdcXs+akFSY4O0JhabJy=9vag@mail.gmail.com> (raw)
In-Reply-To: <157909757860.1192265.1725940708658939712.stgit@toke.dk>

On Wed, Jan 15, 2020 at 6:16 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> From: Toke Høiland-Jørgensen <toke@redhat.com>
>
> To make sure no new files are introduced that doesn't include the bpf/
> prefix in its #include, remove tools/lib/bpf from the include path
> entirely, and use tools/lib instead. To fix the original issue with
> bpf_helper_defs.h being stale, change the Makefile rule to regenerate the
> file in the lib/bpf dir instead of having a local copy in selftests.
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
>  tools/testing/selftests/bpf/.gitignore |    3 ++-
>  tools/testing/selftests/bpf/Makefile   |   16 ++++++++--------
>  2 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index 1d14e3ab70be..17dd02651dee 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -33,10 +33,11 @@ libbpf.pc
>  libbpf.so.*
>  test_hashmap
>  test_btf_dump
> +test_cgroup_attach
> +test_select_reuseport

These were moved into test_progs, they are not independent binaries
anymore, you probably just had old leftovers lying in your
selftests/bpf directory. Let's not re-add them.

>  xdping
>  test_cpp
>  *.skel.h
>  /no_alu32
>  /bpf_gcc
>  /tools
> -bpf_helper_defs.h
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index cd98ae875e30..4889cc3ead4b 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -21,7 +21,7 @@ LLC           ?= llc
>  LLVM_OBJCOPY   ?= llvm-objcopy
>  BPF_GCC                ?= $(shell command -v bpf-gcc;)
>  CFLAGS += -g -Wall -O2 $(GENFLAGS) -I$(CURDIR) -I$(APIDIR) -I$(LIBDIR)  \
> -         -I$(BPFDIR) -I$(GENDIR) -I$(TOOLSINCDIR)                      \
> +         -I$(GENDIR) -I$(TOOLSINCDIR)                  \
>           -Dbpf_prog_load=bpf_prog_test_load                            \
>           -Dbpf_load_program=bpf_test_load_program
>  LDLIBS += -lcap -lelf -lz -lrt -lpthread
> @@ -129,7 +129,7 @@ $(OUTPUT)/runqslower: force
>         $(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower           \
>                     OUTPUT=$(CURDIR)/tools/
>
> -BPFOBJ := $(OUTPUT)/libbpf.a
> +BPFOBJ := $(BPFDIR)/libbpf.a

We can't do that. See fa633a0f8919 ("libbpf: Fix build on read-only
filesystems") for why and why we have this problem with
bpf_helper_defs.h in the first place.

>
>  $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/test_stub.o $(BPFOBJ)
>
> @@ -155,17 +155,17 @@ force:
>  DEFAULT_BPFTOOL := $(OUTPUT)/tools/sbin/bpftool
>  BPFTOOL ?= $(DEFAULT_BPFTOOL)
>
> -$(DEFAULT_BPFTOOL): force
> +$(DEFAULT_BPFTOOL): force $(BPFOBJ)

do we need this? bpftool's makefile will build its own libbpf.a
independently. We can probably optimize that, but see above, we need
to ensure that we build only within selftest/bpf dirs.

This "read-only outside of selftests/bpf" requirement actually made me
realize that we probably need to specify OUTPUT pointing somewhere
inside selftests/bpf/tools subdir to build entire bpftool within
selftests/bpf directory and not touch anything outside. Do you mind
fixing that while you are at it?

>         $(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)                       \
>                     prefix= DESTDIR=$(OUTPUT)/tools/ install
>
>  $(BPFOBJ): force
> -       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(OUTPUT)/
> +       $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BPFDIR)/ $(BPFOBJ)
>
> -BPF_HELPERS := $(OUTPUT)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)
> -$(OUTPUT)/bpf_helper_defs.h: $(BPFOBJ)
> +BPF_HELPERS := $(BPFDIR)/bpf_helper_defs.h $(wildcard $(BPFDIR)/bpf_*.h)
> +$(BPFDIR)/bpf_helper_defs.h: $(BPFOBJ)
>         $(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                            \
> -                   OUTPUT=$(OUTPUT)/ $(OUTPUT)/bpf_helper_defs.h
> +               OUTPUT=$(BPFDIR)/ $(BPFDIR)/bpf_helper_defs.h
>
>  # Get Clang's default includes on this system, as opposed to those seen by
>  # '-target bpf'. This fixes "missing" files on some architectures/distros,
> @@ -186,7 +186,7 @@ MENDIAN=$(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)
>  CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG))
>  BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN)                  \
>              -I$(OUTPUT) -I$(CURDIR) -I$(CURDIR)/include/uapi           \
> -            -I$(APIDIR) -I$(LIBDIR) -I$(BPFDIR) -I$(abspath $(OUTPUT)/../usr/include)
> +            -I$(APIDIR) -I$(LIBDIR) -I$(abspath $(OUTPUT)/../usr/include)
>
>  CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
>                -Wno-compare-distinct-pointer-types
>